Some questions =)
Installation and Configuration
Just to add to what Michael said, I've not tried the new @n8flex skins, but in principle they should work ok with imported Ning media but may not, by default, show all Ning content (groups etc.) so may need some additional template work to do that. Again, you would need to discuss that with @n8flex if you are considering using one of his skins.
You say you have your Ning2 backup ready so presumably you have it all downloaded to your PC via their archiver tool, including all media and image files? If so, check how big it is on your disk so as to assess the size of server needed. Also remember that Jamroom converts and stores additional copies audio and video files so that they will play ok on all devices (desktops, mobiles and tablets) so double (or triple to be safe) the size taken by all these files in your archive.
We do have a 'Domain Mapping' module specifically developed for Ning migrants that can generically map Ning2 urls to their Jamroom equivalent so that should go some way to resolving that issue.
Hope that helps, and let us know if you have any further questions and when you are ready to proceed.
Thanks
Paul
updated by @paul: 05/24/16 03:30:11AM