I'm so sorry for missing this post earlier.
First, for the country being set to "Select Country", the issue shouldn't be that JFBConnect is overwriting the country value set by your other plugin. JFBConnect won't set a profile field to anything specific unless we have a value to set there. So, we shouldn't be 'clearing' another value. The issue is more likely that the other plugin isn't triggering. That can be for a few reasons, like JFBConnect isn't calling the proper plugin trigger that would load that plugin.
Do you know how that plugin works? What step in the profile creation is it triggered on? Is it it a standard Joomla plugin, or is it a Virtuemart add-on that works only within Virtuemart? Any details you can provide will help us understand how best to help get things going.
If you remove the VmConfig::loadConfig(); from the virtuemart2.php (line 28), there is no problem.
That should be fine to remove that line of code. It will be called later during the actual profile import and only as needed. Calling it there is more of a sanity check to make sure that the Virtuemart settings can be loaded. Please try removing it and let us know if there are any issues that you experience. If not, we can remove that extra loadConfig call in the next release so it won't affect you anymore.
Thanks,
Alex