Are you actually suppose to connect your circuit to the earth?
Nothing you do is going to change it's potential significantly.
Having Ground present doesn't stop you getting a shock !
This can be very large if the earth connection is taken from two points in the order of half a mile away.
As is the case with the UK mains earth being taken from the incoming neutral.
No.Wiring regulations state a local earth bonding must be used. Usually taken from the gas supply pipes.
There is a potential of about 5 to 12V AC between neutral and ground. You can, if you like, rectify this and use it as free power because it doesn't go through the meter
and has a route back to the supply in the event of a fault
I had a torch bulb in my bedroom powered this way when I was a boy. Never got much light out of it.