122510 Questions/Answers Website

I'd like to make a question and answers site, but I'd prefer not to do it in a forum environment. I have used one recently that I really like, and I'm attaching a .jpg of how the questions list looks. The site can be clean and very basic, as I'd like to keep the cost as low as humanly possible. Basically, I would need the following functionality: -Post a question -Reply to a question -Reply to a reply -User sign-up -User profile page, w/picture, showing answers and questions they've posted -E-mail notification when a new response is posted, with a link that goes directly to Q/A thread in e-mail notification -An area for Google AdSense ads and 1 banner ad -A home page with links to multiple cities and ability to launch duplicate sites myself using subdomains ( i.e. [login to view URL], [login to view URL]) -questions/answer search -ability to keep favorites -E-mail a question/answer thread to a friend via website When posting or answering a question, users would enter first name, e-mail address (which doesn't appear on the website, and they answer the question "I live in New York/I am visiting New York" and an opt-in question about receiving emails from us.