1. Do we only accept and not follow the project again
If you're banned already then you can't do anything about it, most of the bounty managers don't have time to make up or to entertain you especially if you're already accused as a scammer whether it's true or not.
2. do we have to show evidence that we are innocent
If you can contact the bounty manager or he/she asked you to show some evidence or if you have an open accusation in Scam accusation board:
https://bitcointalk.org/index.php?board=83.0 you can send their directly your evidence and let the older or DT members conduct their judgement against you.
3. Do we accept input from other bounty hunters
It depends if that bounty hunter is a reliable or trusted member of the forum. But anyone can put a negative or positive feedback on your account but only those who're reliable will be accepted (I mean the trust rating will only reflect in your profile if the one who puts in there is a reliable user, for what i've known.)