1. Would it be possible for the Muster Camp to be able to also call upon Eastfold Rohirrim benefitting from the upgrades?
You could alternate between the two and this might give some more flexibility to the Muster Camp and the late-game matchups.
Rather than doing this, it would make more sense in my view to just make the Rohirrim summoned from the camp stronger than other Rohirrim. This would add some incentive to get the muster camp instead of ents, and would also represent that these cavalry are supposed to be Théoden's best men.
2. Could the Rohirrim General perhaps boost the level of the spawned Rohirrim by 1?
Since they cannot benefit from Banner Carriers, I thought it might be logical to beef them to Level 2 at the least if they get an attached Rohirrim General.
Makes perfect sense to me, especially surprised that nobody(including myself) has thought of this until now. I guess fresh eyes really do help.
3. Can Hama's summon of the Royal Archers be elongated?
I find it lasts quite a short while and getting Hama to level 10 is no easy feat. I think it would be justified if the summon timer was prolonged. Another option might be to simply make the summon permanent and limit the unit to 1 on the field. However, I think the first option would be better suited for now.
In terms of having it be a perma-summon, that has already been discussed and(I think) decided against. I would still love to see it be a permanent summon though.
1. Is there any interest in giving a hero from Rohan the ability to summon Rohirrim just like Gamling can summon Peasants? I feel like Rohan plays like the summon faction of the Good factions, just like how Angmar was the Summon faction of the Evil faction. I think either Eomer or Theoden the Cured. I think it might give some interesting alternatives, where you could start with Gamling, supporting a Peasant orientated strategy, while the other hero could promote a quicker cavalry start.
The summon faction for good is pretty clearly Gondor
Good idea though, I would recommend having Gamling summon peasants while he's on foot and Cavalry while he's mounted.
2. The Rohirrim spawned from the Muster Camp can come equipped with bows if you upgrade the camp with the corresponding tent, however I noticed that the arrows seem not to pierce heavy armour, like Rohirrim Archers do. Would it be possible to add this feature to them?
100% agree, pretty sure I've brought this up in the past as well. Their bow switch is very weak as compared to the trainable Rohirrim Archers, they should get both fire arrows and the ability to pierce heavy armor to have them stack up with the trainable ones.