It makes sense for Bane to be working for Jabba. Fistly because Bane's operation to free Ziro was a pretty good advertisement for his skills. Jabba would know that Bane is the sort of hunter he needs to hire. And secondly, Ziro being free may work to Jabba's advantage if he plans to get rid of him. That would be more difficult to do in a Republic prison on Coruscant but now Jabba can can try and capture Ziro for himself. He may well hire Bane for such a job because he knows he can succeed and he has the possible advantage of being known to Ziro, and therefore he may be able to get closer to him. As for Embo and Hondo, it may be a similar situation - Hondo has recognised Embo's skills and so is working with him. Or if they are teamed up, it may be to fight a common enemy, or they may just be working with each other out of necessity.