It seems the service was disabled and not just unloaded. Please reissue the launchctl load command with the -w flag like this.
/bin/launchctl load -w /Library/LaunchAgents/org.macosforge.xquartz.startx.plist
That should force re-enabling. Until that service is running well there will be no joy from double-clicking.
Given this is a very abnormal situation for OSX, someone/something must have run an unload with -w to force it off. A possibility that might do that is if you had been tried installing x11 at some point past the time it was ditched by Apple and all support moved to xquartz as they compete for the right to service X apps. Anyway, let's get it re-enabled and running.
As to opening of layout files, please be more precise. Exactly what did you try and what did the program do? (Commands used, Error messages, etc). BTW - You said "Import" but that is a command used for *.xti files only. Your layouts would be *.xtc files and "Open..." is the correct way to open them. There is never a need to import/upgrade those files between versions, Xtrkcad layout file format is fully upward compatible (and documented in the Wiki).
(Actually .xti format is upward compatible as well, but the difference is that is just the raw track/draw objects and not all the layers and other settings of a Layout).