Thanks NevilleGoddard, the issues you are experiencing are all related to the incorrect PATH when using lightdm.
The semicolon, in a PATH works as "separator" between mutiple paths, and a separator at end of the PATH is not needed, but also harmless.
As far as I can see, the problem is specific to lightdm.
There is already a thread on fbsd forum, mentioning this issue, but no solution so far, (ericbsd posted too):
I'm suspecting that the problem could be related to "how" the user session is launched from lightdm (see "gksu -l" or "sudo -c" for a reference to what I mean).
I will try to look into the details when possible.