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.
A good patch will stick to your tube enough to keep air from leaking out. A great patch will act like a second skin and actually strengthen the tube where it’s applied, flexing and stretching with the tire. After 36 hours of testing, our official endorsement goes to the Rema TT 02 Touring Repair Kit. Its patches do everything other patches do, just better. The edge of the patch is also ruffled, which provides more edge surface area to bond—that’s a good thing.
Professional mountain biker Rebecca Rusch has been on plenty of long rides and experienced enough mechanical failures to know what makes a fully-stocked repair kit. One of her recent journeys, a 1,200-mile journey through the jungles of Vietnam, Laos and Cambodia along the Ho Chi Minh Trail required the utmost degree of preparedness — “We brought with us a lot of extra bearings, o-rings, stuff that you would never be able to find in Laos and Cambodia. Before I go out on these big adventures, I replace every bearing in my bike, my fork got a total rebuild — everything is in pristine condition,” says Rusch.
It has some useful information for basic repairs... not so heavy on the maintenance side but there is some in there. The pictures and drawings are in black and white, but mostly visible. Only a few are difficult to see. However, they are in 2-dimensions and they don't show you HOW to do the thing, they only show you the general area and the part you want to manipulate. The phrasing in the instructions can be hard to follow without a good visual reference unless you're already a master bike mechanic (which you aren't if you're thinking about buying this). So, buy this for general reference and rely on Youtube for video. The two together are better than either one alone.
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.