They do repeat some popular sessions at PASS on the last day, but no guarentee they'll be the ones you want. They record all sessions, and they offer some online or DVD access.

I think that if it's a well known MVP/author, I might be able to guess, but most of them that teach the private classes are pretty good.

I think it depends on whether you want specific information on that topic, or if you want to gain knowledge in a few areas and meet people that might able to answer more questions. At PASS I usually ask for a business card or email from someone if they've answered part of a question. Most of the MS people or MVPs are happy to oblige, or give you their blog URL for followups.