Creating plugin for wprdpress, joomla and perhaps a few more cms scripts

I have an existing dating website with about 10-12,000 members. It currently runs off of a php/mysql dating script. I am very familiar with wordpress and would like a plugin or plugins, for both the admin and user side of wpmu to make it work and search like a dating site. This includes zipcode radius search, css design and manipulation for both the user end and admin end. Basically wpmu modifications inlclude: - Plugin to add custom fields to the wpmu registration page so users can enter city,country,zip (for zip search by distance) and other text fields, tags and dropdowns that typical dating sites have. -Removing unnecessary wp features from the user side so it is a simple to use dating site for them but also still letting them be able to blog. -Users need to be able to upload , picture,music,video,gallery. -Most features can be used by existing plugins as long as the user experience is easy. (changing layout, css and giving instructions) -Creating a widget plugin that can add a dating site to an existing wp blog that draws from my database of users but lets them add users from there blog to both my db and theirs.