Suggest me a plugin for user generated content.

Ok guys, I’m going to start a user generated content site.
Please suggest me a plugin.
Here are the features i need.
Registration/Login
User content submit form upon login.
User can post the content.
A moderator have to approve the content.
Once published disable the edit option for user.
A point system.

In the user content form i need the following.
Title
Desc
Q and A form (question, Answer)
Below that i need one option button ( + Add another Q and A)
When they click that button another form have to show below.

I think this is what i need as of now. Guys please suggest some plugins for these. i’m sure i can’t get a plugin with all these options. So give me some ideas. Suggest me some plugins even if only some of the mentioned feature available. Thanks