Depends on how much is flowing into the pipe. One bathroom sink, 1 1/4"
Minimum 3/4" pipe.
Pipe bore is the actual minimum inside diameter of a pipe, which is not necessarily the nominal pipe size.
It should be 3" minimum, preferably 4.
3/4
1/4" as this is the actual size of the supply connection as the water must pass through the faucet seat.. The spout size can vary from 1/2' -1" depending on make and model and year
3" pipe usually, but local codes may specify 4".
1/2" water lines. Drain line determined by flow rate of showerheads and bodysprays being used. 5.7 gpm or less flow rate would need 1 1/2" drain, which is minimum size allowed.
If you are increasing pipe size it means lower friction loss and possibly more pressure and flow if available from the supply.
Normally 11/2" DEPENDING on developed length of piping and fittings
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.
24".
1"