[AKBLUE]

You have a so called "full auto" selector paddle in a FCG group secured by a retainer plate. This is a bad ju-ju set up for removing the FCG as you have noted you cannot remove the selector because of the disconnector tail and you cannot remove the axis pins because the selector left side pivot traps the retainer plate in position.

Try rotating the selector backwards by rotating it past the selector stop and around from the rear. You will have to lift it out and away from the selector stop and rivets etc.

Once you remove it you can either go back to the shepherds hook or trim the inside of the selector paddle on the left side only to clear the disconnector for removal with the retainer in place etc.
The rear of the disconnector can also be trimmed to allow the selector paddle to clear but this is not as often done and can allow the hammer to fall when rotating the selector above horizontal..

See pic for selector difference.

http://i.imgur.com/VlJyLhe.jpg

 

[AKBLUE]

The paddle... Like, turn the part of the selector lever that looks like, well, a paddle, into the semi-auto shape? That sure would make my life a heck of a lot easier in the future... haha!

Just be sure the right side (closest to the selector) of the paddle will cover the right side of the trigger bar. That is what the "safety" does is trap that bar so the trigger cannot be "pulled". You remove from the left area that interferes/contacts with the disconnector tail only.