Sounds fine to me!
I guess we're on to the resonance abilities now. Looks like we can just use spells for cause fear, remove fear, charm person (or monster), sleep, probably the summon, and maybe some others. Sound good to you?
I'm for "standard action with use of a focus." But I don't think I'd take "chosen instrument" too "personally" for the caprine. I'd just let it be any instrument the caprine has Perform ranks in, rather like Bardic Music works for a Bard. How's that for you?
SRD said:Starting a bardic music effect is a standard action. Some bardic music abilities require concentration, which means the bard must take a standard action each round to maintain the ability. Even while using bardic music that doesn’t require concentration, a bard cannot cast spells, activate magic items by spell completion (such as scrolls), spell trigger (such as wands), or command word. Just as for casting a spell with a verbal component, a deaf bard has a 20% chance to fail when attempting to use bardic music. If he fails, the attempt still counts against his daily limit.
That's pretty good! But I forget, do these have a usage limit per day? Is there something about only being able to use each ability once until accumulating notes again? It's been a long time on these...
The caprine can use a given resonance ability (as listed in the Resonance Abilities Table below) as soon as its resonance score is high enough to qualify for it. Most resonance abilities do not interfere with a caprine's accumulation of resonance notes, so a caprine can use a resonance ability and then continue increasing its resonance score in order to access higher-ranking abilities. The sole exception is the sound of death ability, which prevents any further use of resonance abilities until the caprine resets its resonance score.
A resonance ability may only be used one time after it begins accumulating resonance notes. The resonance score persists until the caprine decides to accumulate a new day's resonance score. This resets the caprine's resonance score to zero, causing it to lose any unused abilities from its previous resonance score but allowing each resonance ability to be used once more.
I would say we leave out the War Machine stuff. Anyway, this is like a slightly lower-powered version of bless (just leave out the saving throw bonus), assuming we choose a duration. That is, IIRC that a round is the same. MaybeFerocity: +1 bonus to hit to companions within hearing range, or +10 bonus to a War Machine unit's BFR. The caprine needs to play his instrument for one round for dungeon encounters, or for the duration of a battle for War Machine encounters. (BECMI only*)
This looks similar, but maybe it's a bonus on saves vs fear?Morale: +1 bonus to retainers, allied NPCs, or +10 Morale to a War Machine unit. The caprine needs to play for one round for dungeon encounters, or for the duration of a battle for a War Machine encounter. (BECMI only*)
Right! OK, well, let's go with your draft on using the abilities.
I guess we should start with the lower level ones.
I would say we leave out the War Machine stuff. Anyway, this is like a slightly lower-powered version of bless (just leave out the saving throw bonus), assuming we choose a duration.
SRD said:Inspire Courage (Su)
A bard with 3 or more ranks in a Perform skill can use song or poetics to inspire courage in his allies (including himself), bolstering them against fear and improving their combat abilities. To be affected, an ally must be able to hear the bard sing. The effect lasts for as long as the ally hears the bard sing and for 5 rounds thereafter. An affected ally receives a +1 morale bonus on saving throws against charm and fear effects and a +1 morale bonus on attack and weapon damage rolls. At 8th level, and every six bard levels thereafter, this bonus increases by 1 (+2 at 8th, +3 at 14th, and +4 at 20th). Inspire courage is a mind-affecting ability.
That is, IIRC that a round is the same. Maybe Ferocity: If the caprine plays for one round, all its allies that can hear the playing gain a +1 morale bonus to attack rolls for 1 minute. But you could change my mind on the duration.
This looks similar, but maybe it's a bonus on saves vs fear?
I'll have to check my old rulebooks, but I think the old versions of the Bard only gave courage bonuses to hit and fear saves with their "Battle Inspiration" and not damage and charm. If that's a 3E addition I'd be inclined to cut the caprine some slack and give it the boost as well.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.