Friction gear systems are a lot simpler to adjust, because the movement of the derailer cable can be modulated as you ride, every time you change the gear- they require less cycle maintenance. Modern index shifting systems are a little more complicated because each ‘click’ must release the exact right amount of cable to allow the derailer to move the correct distance to move the chain from one gear to another. Setting up and adjusting a derailer is not difficult and requires only basic tools, but there is a methodical procedure to follow.
Good bike repair stand. I can't say "great," because it arrived with some small plastic pieces broken. These are small pieces that go between the legs and the supports for the legs to act as a sort of buffer to prevent metal to metal scraping. They are just too fragile, it seems. 3 out of 4 legs had these broken upon arrival. However, these are really only "nice" to haves, not need to haves, and they don't really detract from using the stand in any way. Once you have the stand set up, you don't worry about these at all. The main clamp holds the bike well, if you take care to balance the bike properly. The bike may tilt in the stand if you don't balance it - there is a weight limit to the clamp. I like the included tool tray, but I wish it was more adjustable in height (it is essentially fixed in one position). And the tray could be larger. Otherwise, I am quite happy with this stand. I have worked on several bikes using it, and assembled one out of the box. It makes the job of doing things like adjusting brakes and indexing derailleurs so much easier. The price of this stand is excellent considering the quality.
A bicycle costs anywhere from $250-$9,000 depending what type and quality of bike you want. A utility bike from a department store might cost $300-$500, but experts caution that it will be quite a bit heavier and not as well constructed as other bikes. For a durable, lightweight bike with front-suspension and decent parts, it’s reasonable to pay $750-$1,200. You might be able to pay slightly less, but expect to need some repairs after several months of heavy use.
The fabric attachment system is low-tech, but that seems to be helpful, as it can adapt to seat rails of different widths. One fancier option you might see on more expensive seat bags is a quick-release mount that you install under your saddle. But those have a fixed width, and therefore can fit under seats with only those exact specs. Brooks saddles, for example, are too wide for these mounts.

Change and a $20 bill:   In case your cell phone’s battery dies, it’s nice to still be able to use a payphone if you need to.   Also, the $20 is a great thing to have in case you lose your wallet or have some other mishap.   I’d rather be able to sit in a coffee shop or fast food restaurant when it starts raining while I’m waiting for my friend or cab ride, and a hot cup of tea or coffee or the beverage of your choice and a snack makes it all the more pleasant.  Just try to remember, this is for emergencies, and if you use it, replace it ASAP!
A plastic garbage bag, or $2 disposable poncho:  Just in case of an unexpected downpour or getting caught out after dark.   More than once, I’ve gone for a ride on a beautiful day with a perfect forecast, not taken a jacket and had the weather go south on me.  Being able to cover up can mean the difference between just mild discomfort or a freezing cold, shivering ride home!

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.