The error 100 issue was fixed in the 3.0.2 release. This was caused when Facebook introduced a platform update at the end of September, and only affected specific configurations of JFBConnect on certain servers. Until then, the pre 3.0.2 versions worked fine.
It's pretty easy to upgrade:
www.sourcecoast.com/extensions/jfbconnect/upgrade-guide
As for the Powered By link.. there's separate "Show Powered By" settings in the modules, not just the component. We're working to consolidate these settings in an upcoming release.
Hope this all helps!