Ask The Expert Plugin For Wordpress

I'm looking for someone to develop a plugin for a new website that will be running on Wordpress (Site is still under developement. This plugin will be a Question and Answer plugin where only "Editors or Admins" logged into the wordpress site can answer questions). I'm a programmer myself but don't have time to complete this small task. Please note I will be checking all code to ensure proper (lite weight) PHP coding and other coding is followed with "best practices." 1) Only a selected group of users can answer questions (Editors) 2) Any User can sign up as the site (as subscribers) and ask questions. This should be tied to our Wordpress databases user base. 3) We can create categories for questions which must be selected when the user wants to post a new question. We should also be able to create sub and sub-sub categories. Such as "Dogs" as a main category then "teeth issues" as a sub-category then another category under "teeth" if we choose such as "Incisor" or "K9" for teeth type. 4.) When users click on the "Ask An Expert" link on our page, they should be taken to a nice clean page with all the main categories. When they click on those categories 6) When an administrator replies to a question the question creator can reply again if they choose. However users can not replay once any Admin chooses "Close" for the question. The system should show in the admin area which questions are closed and which are opened. For example I click on "Open Questions" and all questions not closed will show. We should also be able to filter by "Unanswered" questions. 7) In the "Questions" section there should be a search bar that only searches the questions section, not the rest of the site. 8) The questions should post to a custom post type titled Questions and each questions should be accessed by admin for editing and categorizing if necessary. 9) The Experts (Editors) should be able to subscribe to categories in which they are experts in and be emailed when a new questions is asked in their expertise. 10) Question askers (subscribers) need to be logged in to see answers but all questions should be visible by any site visitor. 11) users need to subscribe to the site and payment needs to be processed through paypal. 12)Any other suggestions or features that you do/suggest will be considered. I want to see some wordpress plugin that you've created. Users with wordpress plugin experience will get some extra points. I will only release the escrow after fully testing the plugin on my website (full testing will take no more than 3 days). I will not pay for something not working. If you have question/answer experience of any sort, please send me a link to see your work.