This is a very basic book and unnecessarily repetitive in sections. It does introduce the reader to the basic nomenclature of bicycles and this is helpful when conversing with others. Unfortunately the repetitive sections were not replaced with chapters on 3 Speed in hub gear drives, or coaster breaks, or a chapter on Adult Tricycles and Tandems and E-Bikes.
A wrench that fits the hub nuts:   If your bike has quick release front and rear wheels, you don’t need this, but if you have an internal hub on the back, such as the NuVinci, a wrench that fits is a great idea.  99% of the time, this is a 15mm wrench, but you should check your bike.   A 6 inch adjustable wrench can also work, but it will be heavier, and when using an adjustable wrench, you do need to take more care to not round over the nuts.   A fixed wrench is the best choice.    Some multi-tools have a 15 mm wrench built in, but again, if you have limited hand strength, something with more leverage is a great idea.

Owning a bicycle is a good idea, but taking care of it yearns for an experts’ piece of mind. You should not worry too much about taking your bicycle to a mechanic when you can handle the repairing on your own. It will rather save you the cost of every moment you get into a problem. Grab a pick of one of the toolkits from the above review. I assure you that, absolutely no day will you seek a mechanic for service.

A pair of disposable latex gloves:  Not absolutely necessary, but good for keeping grease and grime off your hands during a repair.  Also, nice to have in an emergency when it starts raining and the temperature drops 20 degrees and you don’t have a pair of regular gloves.   Just keeping your hands dry and the wind from directly blowing on them makes a huge difference in comfort.
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.
The thumb test is the fine art of pressing on the tube with your thumb to see if it’s inflated. During testing, I took a pressure reading out of curiosity, and to the touch, road tires feel fully inflated around 30 psi. How pathetically sad—30 psi!—when you’re probably trying to reach at least 60 psi on a mountain bike, 70 or more on a hybrid, and it only goes up from there.
These folks took me in right away, diagnosed and fixed my stripped handle bar clamps and had me on my way to work in about 15 minutes. Friendly, straightforward, understands the rider's objectives (in my case, how do I get home from work). Not to mention, the fee was reasonable. I have been in many bike repair places in my 6 decades. This is the best.
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.