"Even a smooth wall has many different degrees of texture." I hope you mean roller stipple or brush marks. As long as the wall is uniform in these it will look fine. That is why 'touching up' a rolled wall shows if you use a brush, and the brush cut in around rolled area shows as a slightly different paint texture. Cutting in wider than needed and then not rolling as close as possible makes the effect even more noticeable. A plaster or drywall wall should have no texture at all before painting if it was not purposely applied.

You live in So. Ca. so "freezing is not an issue" wrong! I'm in S.F. Valley & probably 30 yrs ago my bro. who lived 3 blocks away got a rude wake-up call! Loud noise & he followed it to outside the kitchen, seems the water pipe on side of garage had burst & was spraying the neighbors house & freezing so it looked like a fountain. DH & I got the call & went over & couldn't believe it. Never had a pipe burst in South Dakota! It may have been the main valve that went as it took him most of Sun. to get the part & get it fixed. DH & I had insulated our house as it was being built so there is foil-backed insulation in walls & re-insulated attic so it would be warmer in house & cooler in summer but after that I also cover all outside pipes with insulating foam & in winter use an old blanket to cover the main valves. No way I could fix something like that. In your situation, put insulation behind those pipes & might be able to screw on sheet aluminum, paint to match wall, instead of plywood so it can be removed if servicing is necessary. We had about 20 times it froze at night last winter. In 1960's it was maybe half dozen times. Your plants get all watery,wilted looking, early in morning can see ice on roof or on grass. Should be able to do it yourself, If you want to use sheetrock measure it to see how thick it is & get same thickness. Home Depot or Lowe's will probably have some pieces, we got some not long ago from a sheet that had gotten broken. Good Luck

Sand with 150 grit paper, hand(---follow the grain) or random orbit sander. I recommend varnish for tables. Not polyurethane varnish, just plain old varnish. Because it is durable, resists scratching/staining and can be fairly easily repaired. Polyurethane cannot be spot repaired and chips. I buy varnish at Sherwin Williams, but most brand name paint stores have comparable products. The stuff in a home improvement store can easily be way over the Use By date and seems to me to be an inferior product.

I think Jake is correct about things being monumental during construction. I had a similar issue with my kitchen sink cans....joist in the way. The one on the far right is completely off center. My electrician showed me the problem during construction but didn’t offer much in the way of a solution (and neglected to mention the option of a smaller profile can). We tossed it around a bit at the site and decided on what you see here. So not much symmetry, but honestly, I NEVER notice it. I DID during construction. But after it was all said and done, it became a non-issue. I find I don’t look up at the ceiling much. And really, unless one stands squarely in the middle of the window and examines things closely, you just don’t notice it because the other cans will look uncentered as well if viewing slightly from the side. I like things even Steven and pretty much perfect, but a lot of that fades away after a while. Also, when viewing photographs of the issues, many times they seem to be more pronounced compared to seeing things in person.