Install on cold water line.
Yes, you will only have as much pressure as you do with the cold side, probably slightly less.
residual air pressure in the tank, and the pressure switch settings
Its a thermal expansion tank to absorb the pressure when the cold water heats in a hot water tank.
You will get warm instead of hot water. There is a tube inside the tank on the cold side that goes to the bottom of the tank and the hot comes directly from the top. Reverse them and you are going to get the cold water that settles to the bottom of the tank. It will not hurt the tank or anything, it just makes for poor hot water.
Not being able to see the pipe and not knowing where it is, it's kind of hard to know. If it is a cold water line and you have not shut off the hot water tank, the pressure from the hot water will back flow and hot water will come out of the cold side.
If water doesn't go into the pressure tank you will not have water pressure.
Which water tank, well water, cold storage or hot water heater tank.
if all the pipes in the house are the same size the easy answer is adjust the outflow valve on the hotwater tank until it matches the cold water pressure.
You probably haven't re-opened the cold water inlet valve.
By elevating it higher as every foot higher will increase the static pressure almost a half a pound
Terrible idea as the water is heated and the valves are closed there could be a very dangerous build up of pressure and temperature as the T&P is the only safety on these potential bombs. Install an expansion tank at water heater on cold water line to handle pressure buildup.
Take cold inlet water pipe off tank. The dip tube sits below the fitting joining to the tank on the cold inlet side. You can pull it out and replace it.