1) I just tried to register and was successfully logged in and brought to:
www.downticketdems.com/welcome-facebook-user
Have you tried registering since you disabled the SEF extension? If it works, and you want to re-enable it, please look for an option to turn it off for all JFBConnect links. All good SEF extensions have the ability to turn it off on a component by component basis. Facebook can send some really wonky URLs to our application, and it's best if they'r eleft untouched.
2) You should always try to keep the extensions you're using up-to-date. The main com_jfbconnect file will only update the component, plugins, and login module. The remainder of the (optional) modules and plugins are in their own zip. You should download these and install what you use.
3) No problem, and good luck!