Good things, but is it worthless? How much they pay you?
Another big problem will be multiple account that will "jam" the entire system

I agree.
Already a few social networks and forums tried this model but without success.
FB is popular because people can find there friends, chat with them and have fun, not because someone expect to be paid for his activity.
I don0t think such model- paid for posting, can really work in long term and for many users.