Wordpress configuration/modification

I run a website with wordpress, where I ask one question each post. The headline contains the question, the body of the post contains additional information. The following features need to be enabled for registered users within this project: - Answer questions - Possibility to flag answers as private - See a list of already answered questions - See a list of not yet answered questions - Up/down vote questions - Up/down vote answers - Provide own questions (which I need to approve, before they are posted) - Way for user to register (I assume the wordpress own could be used for that) The answers by the user should directly be posted under the post body. Without a reply function (this should not be a discussion board). The answers should be ranked by the up/down votes. Equal voted answers should be ranked by the date the answer were given, Answers flagged as private will not be listed for users other than the user which wrote it and should be not considered by the voting. See pages for unanswered/already answered questions should use a filter by category Please let me know if you need access to the wordpress installation. I would prefer that you work with your own and let me know what I have to config when you are finished. Please also consider that the installation should be still easy to update. Please also tell me upfront how you would solve this project. Are there free wordpress plugins you will use, will you just modify the installation or will you need to code something? Since this is a student project for fun, my budget is tide. If you can't handle that, please do not bid.