1 – I have been playing with that as well. When I create a register page I get 2 different password fields though. I can post a screenshot if that doesn't make sense. I thought maybe they were incompatible, so I quit working on that. Is there any documentation on making these 2 working hand in hand?
2 – I am also installing WP eMember for the paid subscription features. Will all 3 play nice together?
1. I am not sure how you are getting 2 different password field. Usually there should be 2 password input area. One for password input, and another one is for confirming the password.
2. With other membership plugins, you can restrict them from accessing the page, not sure how you'll restrict the number of posts they can make as I haven't tested WP eMember and also there isn't any integration between these two.