Making progress.
My original plan was to cut the blouse out by the original pattern markings, then mark my altered seam lines on the pieces. That way I could always drop back and punt, if necessary. I tried out marking methods before I cut out anything, because I've been down this road before with similar fabric and knew it could be a real treat trying to mark this stuff.
I tried to mark the darts, dots, etc.
I tried carbon paper. Nope. Didn't show up.
I tried chalk. Nope. Ditto.
I tried tailor tacks. Nope. Wouldn't stay in.
At this point I realized that I was going to have to cut the blouse out with the alterations already made. I mean really, I made two muslins, put in and took out 100 basted seams, and made 1000 mathematical calculations getting the alterations perfected, right? So I just jumped into the deep end and cut it out by my altered pattern. I'm a big girl.
I still needed to mark those other things, and ended up with a combination of pin marking each little thing, one at a time, and thread marking it immediately. I ended up hand basting the darts just to make sure I had them in the right spot.
Next up was interfacing. I tried black fusible knit in the lightest weight known to mankind, and it was perfect! I adore Fusi-Knit, yes I do.
I took a picture of it so you can see how it looks:

It's barely there, but gives the collar and front band just enough body to lie nicely and support buttonholes.
Here's the front in progress. Ignore the glamorous man's t-shirt, please:

And the side:
Warning: Sewing Test Ahead!Allrighty now, who can tell me what is wrong with this picture?

This can happen to you, too. At least I hope I'm not the only idiot in this world.