Regarding Auras: I'd give them the same progression as the standard Marshal, and use the same list of auras for simplicity. If you think of others that might work, though, talk to your DM about adding new possible ones.
Regarding Animal Companions: As far as a companion, how about the Bard gains an animal companion, but the companion has to be Medium-sized or smaller and the Bard is treated as a Druid of one-half his Bard level to determine the companion's abilities. That's in line with several variants that give companions to non-Ranger/Druid classes.
Regarding Bardic Music:
Bards by RAW already CAN do more than just stand around and sing.
(Emphasis mine.) Only a Bard's fascination, inspire competence, suggestion, and song of freedom abilities require you to spend a standard action to continue them. For all the rest (which are the songs you'll use most), you just have to spend the standard action to START the music, and then you continue singing as a free action for as long as you want. You can still swing a sword, shoot a bow, or whatever while singing, you just can't cast spells (not a problem here) or use magic items that require completion/activation words. I think leaving it as-is is the best option for that.Originally Posted by SRD