Classified ads (profile database) for language teachers

Classified ads (it´s more like a teacher database) specifically designed for language teachers. It should allow the teacher to be contacted by students using a form, so that teacher´s email is not exposed. Administrator approves all ads and approve all form submissions. It should allow me to require donations from teachers using my PayPal account. So there should be a follow-up system in which a email will be sent to the teacher 2 weeks after student sent a form, asking if potential student has become a student, and ask for a donation to help keep the site running, It should be easy to use this app in all my websites. But first website to use it will be SuperPortuguese.com. Later I will use the same app in [login to view URL] These websites use WordPress.