Thanks everyone!
And oops - for #1 I should have clarified - I was hoping to build the museum on a separate lot (like the property requirement one) from the house. But wild misuse of money prevented me from doing that before the first portrait had to go in--I had to build it on the home lot. Anyway, it sounds like it's better off there, since the portraits can appreciate. I'll have to work with which graphics settings to turn down to eliminate the slight stutter I now have when moving the camera, at times. Everything is maxed, so there should be plenty of room to fix it.
For #3 I don't know why I wasn't counting the spouse/partner being there to save me from twins happening. I see that now. The suggestion about strategically adding pets to the house in case of impending disaster is great - Pets is my only expansion, and I'm glad to see it potentially put to some good use for once!
The bad news is, I tried all kinds of things I found on the internet to get a decent portrait of my dark-skinned founder, that wasn't a featureless or demonic-looking black-and-dark-orange blob. I started outdoors, but it just wasn't working. (I only tried ~5 portraits out there...I probably needed more.) Then I tried placing tons of lights set to maximum brightness in an indoor studio, just behind the camera and right in front of where my subject's face would be (like a real-life photographer's studio), as well as behind the canvas. It still wasn't working.
Well, having played lots of dark-skinned Sims, I was a bit fed up and had had some experience before with what the portrait algorithm seemed to want. I gave it a BuyDebug light behind the canvas, and a halo of them floating around where the subject's face would be. I finally got my first recognizable portraits at that point. I did have a sinking feeling, when I did it, that this was probably not within the rules, and I knew it was a risk. I had somewhat been hoping for a do-over anyway--so I viewed it as a coin toss.
The second time around, we probably won't have the 'fun' storyline about all the misspent cash! Who knows what will happen this time. Thanks again all!