Adverts site code help

I want to show adverts in my site submited by member users. I created a custom form and connected the form data with the adverts dynamic site and designed it as i want.
Issues:

  1. everyone can submit only 1 time
  2. how to make after form submission go pay for the plan
  3. Send an email when advert is approved or not
  4. Admin page design tutorial please.