Designing and Refactoring an existing PHPBB site using WordPress

I am currently in the processes of redesigning my entire user community (Rabbit Stew Lounge). It is currently built on top of PHPBB with a ton of custom code.

I am considering switching the codebase to WordPress. I currently use WordPress for my tech blog (on my own domain) and I love it.

I have some questions and reservations, though. Before I decide to use WordPress to replace PHPBB and all my coding, I am hoping that the following questions can be answered by the community here. Please provide any insight or information you think I might find useful as well. Thanks all.

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1.) I will no longer be supporting a public forum. Instead, I will maintain a small and private forum for registered users. I see WP has a forum plugin. Will I be able to install this, create a few boards, and hide them all from the outside world? Will I be able to add and remove registered users to each forum at my discretion?

2.) Related to question 1, are there any conversions out there to convert PHPBB discussion threads into WP threads?

3.) Instead of supporting a public forum, I will give all registered users their own blog space. Will I be able to allow any number (maybe up to 50 or 60 to start) of registered users to blog in this way?

3.1.) Will everyone have their own RSS feed and private blog page?
3.2.) More importantly, I do not want the members to be able to change their theme to anything other than the ones I define. Would I have control over this?
3.3.) Will I be able to display all blog entries on the home page by all members?

4.) Will registered bloggers be able to post in the private forum? Would I be able to disallow some bloggers forum access?

5.) Will I be able to convert some of the old forum posts into blog entries for individual users? For example, if user X started 10 topics in Forum Y from the old site, would I be able to convert all of these topics into blog posts for that user on the new system? The basic theme is that I do not want to loose 3 years worth of posting history for my members.

6.) Will I be able to show posts from external blogs on my homepage (not in a sidebar, but integrated into the main flow). If so, can a registered user specify that they want to use an external blog instead of my Rabbit Stew blog?

7.) I would also like each registered user to have a gallery where s/he can upload pictures. Can I set up my system so that every time someone registers, they gain access to their own gallery that they can mark private or public?

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I realize this is a lot. But because I am fairly familiar with WP, I am confident that with a bit of advice and nudging from the experts here, I’ll be able to accomplish my goals.

Thanks everyone,
Tod