Customize My Ning Website

Hi I need a developer to help me customize my Ning website. I would like to hire someone who has experience with Ning social network site. Below are some of the elements we would like on the see on the site: 1) A secure way to approve members of the site 2) A secure way to approve video and picture posts on the site 3) Connectivity to twitter is very important (able to update this account from their twitter account) 4) We would like to get both a private and public sections of the site 5) We'd like to have the ability to post video and pictures 6) Post and view comments (like any other MySpace, facebook, bebo, etc...) 7) A cell phone app to update their profile 8) A section on the site where people can post items they wish to sell (similar to craigslist) 9) Instant messenger feature (on the site and on a cell phone)