1. There is a "subscription groups" feature to charge for membership levels, but there is no permission to charge per posting.
2. You can export a listing of user emails which you can import into a mailing list; I would avise against trying to send mass mails with UBB.threads
as you'll likely get your forum emails tagged as spam.
3. The member area has a vBulletin 3.8 importer; when we do have time to work on additional importing coding it'd likely be against the latest forum database schema.