Re: WTF was I thinking, and Stain Removal Question
OK so I had some more time to work on this today. I got a lot more done, but it ain't finished yet...

I sanded all the glue off the headstock face

I filled in the tuner screw holes

I widened the bridge recess route (the original bridge was about 1mm narrower on each side, than a standard Fender hardtail bridge. The string-thru holes line up fine, though) I could have bought 2 or 3 new Fender bridges for what one "vintage" Mats. bridge would have gone for, which could also be worn out or rattle, or whatever, so I decided to just re route for a new bridge. My Skylark has a non-standard bridge, too... I'm OK with that.
THe mounting holes were all in the wrong spots, so I filled those in, too.

THe strap button hole by the neck already was drilled out, I turned down a dowel to fill that hole.

THe other strap button looked like they broke a screw off in the body, a big one... so I dug out my "screw extractor"

and dug THIS out:

I'm not sure what the heck they had in there, it's way bigger than any screw I've used on a strap button. Plus it's brass. Whatever, it's gone now.

I doweled that up too. I'm letting everything dry for a day or 2, before I saw the dowels off and sand everything flat again.
I did get an Electrosocket, but I don't know if it will fit in the output jack hole. I do have a metal plate around somewhere, for the jack to go on. Hm, maybe, measure stuff first before ordering next time?
I really want a set of P-rails for this guitar. Now that it's getting closer to the finish, I gotta figure out something for pickups.