1) In my opinion the ideal number of sounds is between 25 and 35, depending on what kind of sounds are included.
2&3) I want to explain the structure of soundsets a bit.
There are 3 main categories of sounds:
attack,
move and
selectEach of them should have at least 4 sounds for minor heroes and for regular heroes the minimum is 6 sounds. The perfect number in my opinion is 9 each, so that we get at least 27 sounds. These sounds are played frequently, therefore the tracks should not be too long, and not too special for the general situation. Thranduil's soundset has 72 sounds at the moment, because I have to remove some after testing him ingame.
Then there are other categories as well. The most important one for heroes is the recruitment sound, which is played when the hero leaves the Citadel. It can be much longer, because it does not happen that often, so the sound does not get enoying easily. Also, the sentence can be quite characteristic for the hero.
Nearly all heroes also have a dying sound or a sound when they are heavily damaged. This one might be played in the middle of the battle, therefore it should be really short. Adding such a number is possible, of course, but every added sound increases the download duration.
There can also be sounds for retreat, selectinbattle, attackstructure, garrision,...
While in the original game, there were even more categories, in Edain only very few heroes use these, because they will appear only rarely ingame. Of course abilities often have their own sounds as well.
In contrast to heroes, the soundset of units should be much more unspecific and therefore it can contain a lesser number of sounds. Also, the sounds are usually shorter than those of the heroes.
4) The most important thing concerning quality are the background voices. They should be as minimal as possible. Even if something sounds good in a movie, it might be total crap ingame. The human is able to hear things selective, so that he may ignore the background sounds in the movie. Ingame the sounds suddenly pop up, being influenced by the ingame background sounds, which are completly different from those in the movie.
Background noices have to be silent at the start and the end of the sound, and the speaking voice has to be all the time louder than the background noises. Also the volumne of the background noises has to be continous, with no big peaks.
Furthermore, the sound has the best effect ingame, if it is not cut from the middle of a sentence. A smooth beginning and ending would be really great.
The sounds don't have to correspond 100% to the German ones, the only restrictions are that I can't add neither categories nor completly new soundsets for the English version. If some units will share the same soundset in the German version, they will share it in the English version, too.
5) When providing sounds, it would be great if you could sort the sounds to the categories I mentioned above, and name them (f.e. Frodo_attack1). If you use more categories than the number of those that are used, that is no problem, and I can merge them into another one. Also please use underlines instead of whitespaces, otherwise I have to rename every sound.
;;;;;------------------------------------------------------------------------------
;;;;;-------------------------------- Aranarth ---------------------------------------
;;;;;------------------------------------------------------------------------------
AudioEvent AranarthVoiceAttack
Sounds = Aranarth_attack1 Aranarth_attack2 Aranarth_attack3 Aranarth_attack4 Aranarth_attack6 Aranarth_attack7
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
AudioEvent AranarthVoiceAttackStructure
Sounds = Aranarth_attack1 Aranarth_attack2 Aranarth_attack3 Aranarth_attack4 Aranarth_attack6 Aranarth_attack7
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
AudioEvent AranarthVoiceMove
Sounds = Aranarth_move1 Aranarth_move2 Aranarth_move3 Aranarth_move4 Aranarth_move5 Aranarth_move6 Aranarth_move7 Aranarth_move8
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
AudioEvent AranarthVoiceSelect
Sounds = Aranarth_select1 Aranarth_select2 Aranarth_select3 Aranarth_select4 Aranarth_select5 Aranarth_select6 Aranarth_select7 Aranarth_select8
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
AudioEvent AranarthVoiceRecruit
Sounds = Aranarth_respawn1 Aranarth_respawn2 Aranarth_spawn
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
AudioEvent AranarthVoiceHelp
Sounds = Aranarth_help1
Volume = 160
MinVolume = 130
Limit = 1
Type = world player voice
SubmixSlider = voice
End
The German soundset used the category attackstructure, for which there are no specific sounds in English, therefore it does use the standard attack sounds.