The ALT-Enter issue is because I am using the RGD executable replacement. It's something I have to restore manually. The mouse issue was a simple error--I neglected to set the new "mouse multiplier" when going to fullscreen, which tells the game how big each of the mouse zones in a window should be.
You're right, I could've just hooked these up real quick and went on my way. I had a fixation on doing everything "the right way" e.g. building my keybinding menu and -then- hooking up those default keybinds, which sucked up a lot of time. I was worried that I'd have to tear it down and rebuild.
Basically, instead of doing these sort of quick-and-dirty fixes over the course of the month just to get a tech demo out, I ended up doing them all at the end. I ought not have been so scared of doing work twice, and more worried about not getting to do it at all.