Cut and installed the sheathing for the middle cavity of the front wall tonight. Sorry for the close pictures, the garage is a mess and I couldn't get further back with a clear shot right now.
This is my first experience cutting sheathing (or drywall) with outlet/switch holes. Needless to say, it is quite the learning experience and I'm not very good at it so far.
The first hole I cut was the double outlet box. It was tight, but good.
The second hole I cut was for the switch box, which I thought why not make it a little bigger by about 1/8" all the way around just to make it less tight. Well, you may be able to guess that the fact that I measured both sides from the "outside" (being the door opening) so that meant, because the overall width was about 1/4" narrower than the door openings (which I was OK with) ended up making the hole for the switch box about 3/4 to 1" too far to the left. DAMN!
I ghetto'd it to close it up for the night, but I need to fix it. I think the easiest thing I can do is pull the switch plate off, cut the hole even wider to the left, take another piece of sheathing put it in behind (like you would do when patching a drywall hole) and then cut a piece of sheathing to attach to the new piece hidden behind.
Also, I need to buy some wire blocking plates to put on the studs where I have wires going across the wall to be safe for future screws, but I don't know what those are officially called.
NUTTSGT, here's a picture of the concrete tube stuff I have.