Tim,
Hopefully, everything is answered below, but if not, let us know:
1) JFBConnect has been tested with the betas and RC of Joomla 2.5. We're still going through our extensive test suite with the final stable release, but aren't expecting any huge problems. We're fully committed to 2.5, and will support any issues that arise.
2) JFBConnect's profile integration currently only works with VM 1.x. We're working to add profile importing to VM 2.x, and expect to have the first plugin release for that out in a few weeks.
3) JFBConnect leaves 'normal' Joomla registration up to Joomla itself. If you have the Captcha feature enabled, JFBConnect doesn't interfere with that. We only add an additional registration process using Facebook credentials.
4) The 'confirm' step on the demo is simply a restriction by Facebook. Since we have so many test users that use that site, they hit the Like button, then undo the Like. It looks spammy to Facebook, so they (automatically) add the "Confirm" step to pages with 'odd' behavior. Most sites will never see that step, and it's not something controllable by JFBConnect.
5) Yes, the Google+1, LinkedIn Share, and Twitter Share buttons are all included and can easily, or automatically be added to different parts of your site.
6) They are moving to a different HTML5 based system. We do not support that yet, as there is no fallback, so older browsers will not display those social widgets. We expect to move to the newer system later this year (as an option), but the current XFBML tags are still fully supported and fully featured solutions from Facebook.
7) We have a full 13 page configuration guide, which includes information on app creation. It can be found:
www.sourcecoast.com/jfbconnect/docs/configuration-guide
Hope that helps,
Alex