phpBB Integration

I have a website that I control access to content with using aMember. I am looking at having phpBB plugin to use on my existing site. Can you answer the following queries Alex pls:

1. I want people to be able to post on the BB without HAVING to sign up to a subscription. What is the best way to do this. Should I make them register through phpBB in order to post if they have not yet taken out a subscription?
2. When a user subscribes I don't want them to have to then fill out another registration in phpBB in order to start posting. Can they use the username and login from there aMember registration?
3. As an idea would this scenario work to let users access the phpBB ONLY if they were signed up to aMember:
a. Have a product (Product_A) active in aMember for access to my restricted content?
b. Have another product (Product_B) setup in aMember but a FREE one, i.e. the idea is they have to go through and create an aMember account but doesn't really do anything as far as accessing content goes.
c. Can I now let both these groups that are signed up to Product_A, and Product_B be able to post in the phpBB forum, and NOT let anyone just sign up for an account in phpBB on its onw (can I disable this). If so then what happens when a users membership (aMember) expires, are they still allowed to post in the phpBB.

Is the above the best way to setup aMember and phpBB working together, or is there a much better way to achieve this. Sorry its just not clear from the text I have come across on the website to clear up all apparant ambiguities. And I don't want to have to spend ages sorting problems out when I try and synchronise aMember with phpBB.