Re: Zabuza VS Kimimaru (who will win)
Probably Kimimaro due to his Bone Field technique as a trump card.
Realistically Zabuza is going to try using his Silent Killing combo, be it his signature move and all. I don't think that this will work on Kimimaro however, since can grow bones out of his body and possibly stop Zabuza's attacks mid-strike (even if they ARE surprise attacks).
Next comes Water Release jutsu in the forms of clones, water prison, and powerful offenses like Water Dragon and Water Vortex. These are actually quite useful here and may cause Kimimaro some trouble, but a body of water would need to be near by to ensure maximum effectiveness.
Overall though I think that a water prison would be the best option on Zabuza's part. However if Kimimaro can fight the water pressure involved in this jutsu, he could still win anyways. Or perhaps he'll use his bone field jutsu earlier on and corner Zabuza eventually.