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.
Unlike floor pumps, most hand pumps do not have pressure gauges. To get readings during my original round of testing for this guide, I built a special rig involving simple hardware-store parts. But the experts I spoke to seem divided on the usefulness of gauges. Half thought they were unnecessary, added bulk, and drove up cost. Why do you need a gauge if you know 100 pumps inflates your tire? But the other half liked them, because the “thumb test” is notoriously inaccurate.
Whether you ride a single, 7, or 10 speed bike or anything in between, you will need a slightly different chain. The major difference is that they come in varying widths to accomodate the different spaces between the gears, but quality of construction is also a factor in choosing a chain. Inspecing the chain should be a part of your regular cycle maintenance procedure- It’s important to keep a chain well lubricated, but oil will also attract dirt and so different oils for specific riding conditions are available. Remember to clean your chain regularly to get the longest life out of it and the gears.