These are some great ideas, especially the simple ones like bringing a garbage bag. That’s something so easy and cheap that it’s easy to forget entirely, but as you say, it can make a huge difference in the right circumstances. It’s also good that you discuss some minor bike repairs. That’s another thing that can salvage or destroy your ride. You want to be as prepared as possible for the best possible experience.
We like, and recommend, the Crankbrothers Speedier Lever. If you have to pick only one, go with the Pedro’s, but if you want a backup or have some hard tires to unseat, Crankbrothers is a great choice. It’s only one lever (as opposed to a set of two, like the Pedro’s) and it’s longer, so we didn’t pick it over the Pedro’s for portability reasons. But it’s an excellent tool. It has a wide handle you can grip with your whole hand. Like the Pedro’s, the tip is the right size and shape to prevent slipping and stay in place, and the shape of the handle happens to protect your knuckles if you do slip. Even in situations where I didn’t need it, I liked having it because it made me feel like a pro.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.