hi, the questions can be answered quickly:

1- vBulletin have a API that help on integration with external tools... so you can find a software that is acting like you ask, for models, and it would require some coding to integrate it to vBulletin, like for authentication of members, but that's possible. aMember is a good start for subscriptions between two engines

2- the template system is very flexible, as example, you can have a unique style for each forum inside vBulletin, and you can let your users modify their CSS in their own profile, like in MySpace...

3- the best place to Require a Paid Service is in the forum of the same name on this site... be precise, without too much details, give a ETA, budget, description of tasks, and require to have a popular/in demand coder... people with 3 posts and no portfolio will never be good coders... they can trick you with smalltalk.