1/2 inch will easily do that.
Hole or pipe size is not the only factor that determines flow of cubic feet per minute. The other factors are presssure and resistance.
No, water expands in size when frozen. That's why ice floats on water, and why pipe bursts occur when trapped water in them freezes.
1"
Fixture unit demands and developed lengh
Nothing as long as the pressure pipe is not used for potable water as you cannot make a direct connection and depending on the GPM flow what size the larger sewer pipe is as 1 GPM (pumping) is considered 1 fixture unit when sizing the drainage system ALSO make sure the pumps system enters at a right angle 45 deg so your not eroding the side of the larger pipe out
Check pipe size for hot water or if galvanized pipe used, pipe could be clogged inside with rust and scale.
If the electric motor requires 2 hp to run, then you need to supply it with no less than 1,492 watts of electric power. It makes no difference what job the motor is used for.
1/2 in. pipe commining to it and then you could bring it down to 3/8 pipe
A lot less because the water is flowing if it is exiting and it depends on the water pipe size.
Depends on how much is flowing into the pipe. One bathroom sink, 1 1/4"
Depends what size your pipe is
0.255 gallons per foot of pipe. A 10 ft long pipe that size holds 2.55 gallons.