7
It's not allowed under the current system. See Bounty-like facility for rewarding excellent questions and any of its duplicates for the rationale.
The problem with offering bounties on questions is it doesn't encourage any behavior from other users. When users see a bounty available on a question, it encourages them to provide a detailed answer in an ...
3
From the bounty faq:
If two or more eligible answers have the same score (if their scores are tied), the oldest answer is awarded the bounty.
3
I had a look earlier when there were 4 questions & now, which has 5 featured questions, and both cases the number's shown correctly. It's probably a caching issue.
Only top voted, non community-wiki answers of a minimum length are eligible