I'll give you my opinion on your questions; I've been through a lot of this but I'll admit I don't have the track record of some others who post here:
1. Materials from Lowe's are average quality. I've used tanks from them on my last 2 wells and they worked fine, but I moved or upgraded equipment within a few years. Unfortunately Lowes is more focused on price than quality. Specifically on the pressure switch, Lowe's sells a China-made one but Square-D may also be manufacturing overseas now so a brand name is not always a sure bet . You can often (but not always) get better quality from a supply house or a tradesperson. The problem with buying from a supply house is an individual will often be charged dramatically higher prices than a tradesperson would. I've experienced that first-hand.
2. Generally you can upgrade to the higher pressure, assuming your pump is capable of producing that higher pressure (it should be). But for a constant tank size your pump will cycle more at the higher pressures. Also you will need to raise the air pressure in your tank.
3. A bigger tank is better, your pump will cycle less. It should be matched to the pump output, which should be matched to the maximum usage. I've read that you should have a minimum 2 minute run time on the pump.
4. I use teflon dope, but I think either dope or tape is fine. With regard to soldering you don't want to solder to that male adapter when it is connected to the tee; the tee acts like a big heat sink and sucks away all of the heat from the solder connection. Instead solder a 1 foot or so pipe stub to the male adapter before installing to the tee, and then couple that stub to the existing pipe. That extra one foot distance from the tee will work wonders when soldering the coupling. Also use a hotter mapp gas torch, you want to apply more heat for a shorter time. And to prevent water from leaking back, stuff the pipe with some white bread to create a temporary seal. Works every time, although you sometimes have to clean the bread form your faucet aerators afterward.
5. A CSV seems to be the way to go for maintaining constant pressure and minimizing pipe cycling. I am considering for my using with my water-source heat pump; now I have an 86 gal tank but I'm still cycling like 10 times an hour. Cycle Stop Valve is the brand, but there may be other brand valves out there that maintain constant pressure.
6. I prefer the brass tank tees, the union set-up seems geared more toward speedy installation. Spend a little extra time to eliminate the extra connection.
Oh, that's a check valve and not a CSV in that last photo.