Water main coming into house usually 3/4" K copper pipe. Depending on local Plumbing code, fitting usually is flared or soldered.
Conduit fitting is used on metal pipes that house electrical wires. These fittings are not only to connect the various pieces together, but to keep a relatively water tight seal to the wires.
Dielectric union
You shouldn't have a problem finding a reducer at a home/builders supply house.
Yes.
A pressure tank for a pump & well potable water system only has one connection. To connect the pump and tank to your house's water inlet, simply connect the tank and pump together with pressure rated pipe, SCH 40 PVC works fine. In that line, cut in a TEE fitting, and from that T, connect the house inlet with a valve to shut the water off.
The person who had the power company connect it's service.
The option is generally you have it and pay for it -or you don't
Use an air compressor with an adapter fitting that will allow you to push air in through a spicket on the tank. I made an adapter with a water pressure tester gauge (that is made to attach to a water (hose) spicket.) I then took off the gauge and installed a quick connect air fitting (standard on air equipment and air hoses).
Every house has service boxes with fuses outside of the house. Traditionally there is electricity fuses outside, cable fuses and water lines that can be shut off from outside the house.
Supply coming from water source is a water service line.
Taape or joint compound on the threads the same as any other pipe fitting, but not on the threads where the two halves connect.
To install the water return fitting above the ground pool, you have to switch off the source. After this you can then install the water.