Are those water lines? The off-white one looks like an electric cable, which I don’t like (potential for it to rub against the edge of the hole and wear the insulator).

$83 a tin. What makes it worth that?

I don’t think it matters which color samples you get. Everyone has to be able to reproduce everyone else’s colors. The only differences might be that if you use a different company’s color samples, then it takes them a little bit more work to do the color match, rather than simply giving them their company’s name for a color; and you may get a guarantee on the color if you use their own colors.

As a DIY homeowner that paints maybe a room a year on average, my current favorite paint is HGTV Home Showcase by Sherwin Williams, available from Lowes for about $50 a tin. It has a red label. It’s a small step up from the cheapest, but it’s still far from the most expensive; but it seems to me that the gain in quality that you get from paying a bit more than the cheapest is much more than you would expect, so it’s got a great quality-to-price ratio. With the cheapest paint, you have to work to get it on the walls smoothly, but this goes on nicely.

This is all great advice! I would add:

1. Youtube is great for how-to videos that will allow you to take care of a lot of small repairs more or less for “free”, but it’s not interactive. Sometimes you just don’t know the right term to use in an internet search, and you need to ask people. Use this Lemmy community and/or diy.stackexchange.com to crowd-source solutions to your problems (explain the problem and post a few photos) that you can then watch videos about to get the details right.
2. In regard to tools, I like the following rule: when you first need a tool, buy the cheapest one that will get the job done; then when it eventually breaks (because you’re using it for new jobs) buy a good-quality one. This way, you’re not spending extra money on stuff you’re only going to use once or twice, and when it comes time to buy something you’re going to have for a long time, you’ll have some experience so you know what features you want.
3. Laws in the United States allow a lot of work to be done by the homeowner, especially when you’re replacing “like for like” (e.g., swapping out an electrical socket); but if you’re doing more than that, check on whether you’re going to need a permit from the local municipality. In other countries, laws may require licensed contractors perform certain work (e.g., electrical and plumbing).
4. Take care of emergencies, but then get comfortable. It’s your home, you’re going to spend lots of time there, so you don’t want to be living in a construction zone for a decade. Work towards a standard of living that you (and your family) can not only tolerate but have some level of comfort in.