[chrishajer]

> The forums has a whack load of sub forums along with ones only visible by certain

> members, I’m wondering if it is possible to make sub forums along with special ranks

> along with moderator and admin?

Yes, you want the hidden forums plugin:

https://bbpress.org/plugins/topic/hidden-forums/

> I’m also wondering if bbpress is easy to setup with Yahoo Small business hosting?

So long as the server has PHP and MySQL, and can send email, then it will be fine. If it can’t send email, then there are plugins to use an external SMTP server.