Integration in existing community site

[kangoosin]

Hi,
I have an existing community site where members have created accounts with username/password and a profile.
I would like to integrate now a forum to that site.
The integration should be seamless to the members and I cannot change the existing architecture.
Therefore I have the following question concerning VB:
1. If a user has already registered and logged in the website, is he able to access the forum without having to register again? He shall be able to post or moderate if he was given additional rights.
2. If a guest visitor is browsing the site and goes to the forum section, is he able to read the posts without being able to write? At the same time, he should be invited to register but not in the forum but the site itself.
3. When some is writing a post, his profile info is shown in the left side (username, avatar, ...). Can those be taken from their existing profile on the community server (username, age, profile picture, ...)?

I had to drop already few forum solutions due to the impossibility to integrate those properly. So I hope VB will be the right one finally.

Thanks for your help,
Julien