All multi-tools are not created equal, but most with a plethora of features will get plenty of the jobs done. I personally like, and use often, the Lezyne RAP-21 LED tool, which will run you around $30. I like it because not only is it a high quality construction, but it has just about everything you’ll need, plus a sweet mini light. This will give you a chain breaker, spoke wrench, disc brake wedge, and all the most often used Allen keys and drivers. We’re talking a decent number of tools for 1/4 of what they would cost buying them separately.
A two-stage hand pump tries to marry the best features of both types of pumps: the quick inflation of high volume that can achieve the higher psi ranges of high pressure. But to steal a quote from our floor pump guide, “You pump eight times or you pump 10 times—what does it matter?” That’s a quote from Daimeon Shanks, who at the time was a mechanic for the Garmin-Sharp pro tour team—that’s right, Tour de France, baby.
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.