hmmm, Taun Tauns you say? Sounds really tough to me. If making a convincing ATAT or ATST animation in BF2 is highly difficult, then I'm guessing that animating a Taun Taun as a vehicle would be a monstrous task. But...thats not saying that the team isnt up for the challenge...
I would love to see a Taun Taun in-game, but I'm not going to lose sleep over it 
Shooting while riding would be cool, might be a bit difficult to control tho. Maybe a control scheme similar to a tank, but make it look like you're shooting in first person, that would be cool. Althoug it would be nice if the controls were the same as infantry where the A and D keys would be strafeing, it would be a faster method of transportation, but wouldn't improve your firepower at all.
Any chance that they could move and make sounds while unnoccupied? They could stand in the same spot, but maybe move their heads and make snorting sounds or something.