Profile data fields:
I'm currently working on trying to get member's profile fields (location, website, etc.) to make the transfer to the new site. I'm working on creating an importer and cleanup tool since the importer makes a real mess of those profile fields and doesn't import the actual data.
Passwords:
Unfortunately, passwords will have to be reset when logging into the new site the first time. I can't do anything about that since the two sites use different password hashing and salting.
Avatars:
Still don't know yet if I can make those transfer over.