You don't need to set a post requirement to have access to a forum. Any MBA forum, invisable or no, you can go to the admin area (which goes right to the member page) and click on the members you want to have access and they will regardless of post count. The MBA forums have a lot of flexablility, you can set them however you want them for access, by post count, applying, or manually setting the members.

As far as mods, admins, and board mods... yes they do have the same here as on Ezboard (sorta...). Admins of course have access to everything, mods you have to set by individual forum. If you want a mod to have access to modding all forums,just set their mod privileges on every forum. Otherwise you can set certain mods to certain forums.