As for the first issue, it's been resolved in v2.1. Just upgrade (install on top). BTW this issue was not visible to everyone, as it relates to specific server setups.
As for the 2nd thing you mention, that's a misconfiguration on your side. If you want your users to be able to control these additional fields, you need to provide a menu link for them to "edit" their account details. Just create a menu item to the default user edit account view ("Users" component). K2 extends this form and since the plugin extends K2, your users will see the additional fields.
Sad to hear that you had such problems, although the one where jbetolo keeps being part of the page rendering even though it was uninstalled is very odd. The only way for this to happen is if you had system cache turned on and the page was cached while jbetolo was in effect. Regardless I wish you had contacted me and we could have tried to solve the issues you had instead of reading about it here as the first encounter of the issue, which I feel doesn't hold for an open source and free extension where some amount of collaboration is the least that can be expected of both users and developers. I do my best to assist users that contacts me.
Also, be aware that some of the other extensions we tried can break your site (and by break I mean destroy it). I cannot express enough how well developed and supported JFB Connect is. It is extension heaven for those who hate rebuilding their sites after bad coding sets their Joomlas on fire.