There is one problem, Aranarth was born long time ago after Araval death. So, they can't be together in the one faction. This is the same as for example Gimli and Bard in one faction.
Good idea about cavalry (to be equal to "Rohan answers"), but in my opinion that should stay similar to power ''Gondor Army'' with integration of elven units. Power "Gondor Army (or "Army of Gondor", can't remember now. )" have nine battalions: 3 Gondor Knights battalions, 2 Gondor Swordsman, 1 Tower Guards, 3 Gondor Archers. My preposition is that 3 Gondor Knights battalions stay, 3 battalions of Gondor Archers to replace with some elven archers (Imladris's Noldors with nice armour), in place of Tower Guards to add one more battalion of Gondor Knights or some better swordsman, and instead of 2 battalions of Gondor Swordsmen to add 2 battalions of Mithlond Sentries.(Really find that swordsman useless)
Second idea is next:
http://postimg.org/image/3sikpeieb/
Maybe it looks complicated, but I think this way Lore's aspects are completely satisfied. (Because combined forces of Lothlórien, Rivendell and Gray Heavens helped Arnor. Lothlórien units would be too much. )
If all of this make things too complicated (but I think not) from aspect of comparison with Gondor faction, then we should use your suggestion about only cavalry.
But Gondor Army spell now summon 9 units and one hero. I think that spell with 9 units and 3 heroes is too much for one spell.
In Addition, Rohan answers summons 6 battalion of rohirrim riders and 4 heroes(Merry, Eowyn, Eomer, and Theoden).
I think it is not necessary to add Lindon units to this spell. They are already integrated to Outpost.
This is my intention for Arnor:
Hobbit and Lindon as mini-faction only for Settlement and Outpost
Imladris and Gondon as mini-faction only for spellbook
Agree, Lindon fortress should be at Outpost, and Rivendell's at settlement. My suggestion is to use current model of Lindon's Spire in both cases.
For Rivendel could be used model of Spire lvl 1,2 or 3 (Think that lvl 2 is most fitting.) because it can be builded on settlement, and for Arnor Sprire lvl 4 of course.
I would also like to see Mithlond Sentries, (As you said Arnor needs some Tower Guards comparison, because this comparison miss, like there is comparison DolAmroth swordsman and Guardians of Arnor) and about that DolAmroth Knights comparison, I would like to see Mithlond riders with spears more then with swords. (Because of difference between them and Wind Riders and I found Spear/Pike weapon of Lindon's eleves. Because of vanila probably ) Anyway, usage of current Lindon elven model into integration of this riders could pass, and their usage into Mithlond Sentries's model is very fitting. These Lindon elven units of course:
In this case Círdan don't need that upgrade ability. And using of Palanír of Elostirion should be able only if Círdan is produced or somehow should stay requirement for Círdran's level 10. (This will complicate things, but it's justified from Lore aspects of that stone. From Lore is known that only Elendil could use that stone, it's needed great mental potential of person who wants to look into any of stones.) About mount, it is irrelevant in my opinion, because Círdan stays unit supporter.
I think that the current Cirdan's ability for Lindon Spire should to stay in Imladris.
But Maybe only Lindon Spire level 1-3 for Imladris and level 4 for Arnor's Outpost.
You're right, the spear is better for Mithlond riders.
About Cirdan, yes maybe mount is not suitable for them.
Also, I noticed that he has ability "Journey to the West". I think that this isn't fit at the time of the fall of Arnor. This ability is more suitable in Imladris at the time of Lord of the Ring.
I have some ideas for Cirdan abilities in Arnor(he will be more offensive):
Level 1: Ring Narya (same as now)
Level 3: Quickly help for Arnor
Cirdan with his army rush to help Arnor. For 30 seconds Cirdan and Lindon units deals +25% movement speed.
Level 5: Healing Aura (same as now)
Level 7: Guardians of Lindon
Cirdan summon temporarily battalion of his best warriors. So, they will not be removed from Arnor.
Level 10: foresight (same as now).
I am for this implementation with few exceptions. I also found hobbit role important in Arnor history. During reign of king Argeleb II (1589-1670 T.A.) Shire was granted to hobbits, before that it was hunting grounds for Arnor's noble society. So Shire survived about 500 years of war between Arnor and Angmar, so it needs to have part into units production and warfare.
Nice model of Hobbit farm, like it. I am for implementation of that economic structure and that units but I am not for removing hobbit unit reinforcement power. (I will explain this on last part of mine comment.) In my opinion Hobbit archers should stay part of this power and their slot on hobbit farm should take hobbit donkey riders from 3.8.1. Why this? In this suggestion Arnor will probably have 3-4 different types of archers, so hobbit archers free production from farm is simply too much. This way hobbit archers stay unique, and hobbit ridders are not so strong units, they don't have knock back ability, their main purpose is fast movement over map and killing weaker units. If donkey riders are too much (Useless cavalry), then hobbit farm should produce only militia. Also that hero "Tuk" should stay and his model and palantir and voice, should be improved. He should stay because of nice background story in my opinion(Leader of Hobbits in battle with Goblins, and that Golf stuff is epic! )
If I know, Arnor has only three archer units in 4.1:
1) Arnor archers
2) Arnor rangers(two additional forms are just improvements for this unit)
3) Guardians of Lindon(this unit will be only temporarily in my concept)
Maybe they can have the passive spell in spellbook:
Support of hobbits :
Hobbits go to thhe battle against the enemies of Arnor. Now you can recruit Hobbit archers in hobbit farms and you can recruit Hobbit militia +25% faster.
In addition, Hobbit archers had an important role in the Battle of Fornost, I think they should be permanently in hobbit farm.
Maybe this hobbit hero "Tuk" can be new scout for Arnor and maybe he can summon this hobbit donkey riders. They are fit for the role.
At this point, we have most disagreement. That starts with Aranarth, that man was First of Chieftains of the Dúnedain! He was not armored prince. (He could be, but very short period of time) At first place, with his people he fled to Lindon when Northern Kingdom was destroyed, and when his father had ship accident and died/missed, by right, this made Aranarth now King of Arnor, but since kingdom was lost he could not claim the title. Instead that we have birth of Dúnedain ranger order, and he became first of of the Chieftains of the Dúnedain. He also was chieftain for longer than any would be after him, ruling for 131 years. Point is from lore aspects, that Aranarth should stay Faramir's comparison on Ranger's camp. His second role (Prince of Arnor) should be removed. That "Heir" model should be used for King Araphant model.(I found that current model of king Araphant is very weird and inappropriate.)
About scout hero, thing is simple, I won't add any new hero except King Araval or Arvallen. Galdor is not option in suggestion like this one. I would keep Carthaen for this role because two reasons:
1) He was a character created in the Electronic Arts video game The Lord of the Rings: The Battle for Middle-earth II: The Rise of the Witch-king. There is no Lore information about him or his existence.
2) In time of this part of Arnor's dynasty (Araval /Arvallen-Araphant-Arvendui-Aranarth) Carthaen was already destroyed. Destroyed by plage and by magic of Witch King. So role of this region of Arnor should stay minimal (I could say that Shire had smaller losses during plage) and in that way this scout role for this fictional character is enough. (In other words, he don't deserve any other role!)
Some skill change is ok for him, to buff him, after all he isn't some hobbit.
This concludes next: There is no need for that Hobbit aid power change, and there will probably stay that two options for Dúnedain Rangers upgrade (So there will be three different Rangers units and one basic Archer unit = 4 different kind of archer battalions )
Sum:
Glorfindel moves to palantir power.
Cirdan stay with minimal difference. (Stays in support role.)
Araval /Arvallen (New hero for killer role,described above.)
Araphant gains new look. (Model of Aranarth "Heir" model, stays in support role)
Arvedui stays with same model. (Stays in tank role.)
(Some proposal for new elite units when he wears ring would be nice for future. )
Aranarth became first of of the Chieftains of the Dúnedain and that is his role, disabel that "Heir" choice. (Lore!)
Carthaen stays scout. (From my point of view he can't replace Aranarth in ranger camp ever! )
That is my suggestion and some objective answer to your post.
I will try to make some good topics in future about Arnor and changes I think Arnor deserves like Mighty Northern Kingdom and home of The House of Isildur.
I am starting with this one: http://en.modding-union.com/index.php/topic,31402.0.html
Aranarth was Chieftains of the Dúnedain but after the destruction of Arnor kingdom. So, Prince form of Aranarth is fit for Arnor faction.
He should start as a prince but later to become Chieftains of the Dúnedain.
Similarly to Aragorn which start as Chieftains of the Dúnedain and later to become King of Gondor. I think that Aragorn and Aranarth can have same role - hero killer.
If Carthaen is dead, he should not be in Arnor as scout. I do not know, maybe Edain team used his character from game but they ignored his role no-canon role and death in the campaign.
Maybe Arnor does not need this no-canon character and Aranarth can have two roles in Arnor:
Aranarth(prince form): hero killer as Aragorn in Gondor
Aranarth(Chieftains of the Dúnedain form): units support as Faramir in Gondor
He can be available in Arnor fortress(only prince form) and you can use his Chieftains of the Dúnedain form only if you build Rangers camp.
So, Gondor/Arnor will have these roles for heroes:
Pippin/hobbit hero or Carthaen - Scout hero
Denethor/Malbeth - Hero and unit supporter
Beregond/Araphant - Building supporter
Boromir/Arvedui - Tank
Aragorn/Aranarth(prince form) - Hero killer
Gandalf/Gandalf - Mass slayer
Faramir/Aranarth(Chieftains of the Dúnedain form) - Unit supporter
Imrahil/Cirdan - Unit supporter
What do you think about this ideas?