Hello , I need your advice .
A potential client asked me to have a tool on the site that allows members to be able to write questions on various topics , and that he himself could also respond by triggering comments and other responses .

Asks these two circumstances:
1 . For each insertion of a new post all subscribers are notified by email or by post or with a copy of the email that alerts them that something has been updated
2 . Weekly or every configurable to be sent to all members an email summary of the latest posts
3 . A question or an answer must be set as private, then only see who is speaking , or the public who see it all then .

Must also have a restraint so that a person does not write strange thing .
Even entries must be moderated to avoid enroll people who are not admitted .

There is an Add-Ons in Concrete5 that will allow me to do this?

Sorry for my english ...
Thanks for your help !