Transferring an existing site to Ning or similar

I have a social networking site, www.soulalert.com. I am thinking of transferring it to Ning or other similar service, but need some advice and if I proceed, then someone to do the work. Questions/concerns are: - Is Ning the best one or is there a better one? - Can the brand be made similar in Ning (less black, a few changes but same logo etc) - ie so members will not be adversely affected? - Does anyone know if with Ning they own the copyright on all code and content? If so am I being unwise in transferring a site I have paid a fair bit for to a free site like Ning? - Can all data, user logons, forums posts be transferred without issues? - Can you have a talkshoe widget on a Ning site? - Can you add a paypal service on a ning site with ease? - Can you have downloads, eg audios, eBooks, articles? - SoulAlert is made using PHP, Ajax and not sure what else. Please let me have any comments to the above and cost. Thnx