No, there is no requirement for a liner. It is not even necessary to have recirculating water, but it would certainly help in keeping your pond clear. How far away from your house would you like this pond?

Running power out 50' is a medium duty job. I did something similar but I had some assistance from a local guy with a small duty industrial trencher, scoop, tractor, who cut a narrow trench while he was doing other things. You can run electric wiring thru glued together pieces of plastic conduit (essentially the same as the heavy pvc water pipe). The ends of the wire and conduit get glued into plastic electric boxes at both ends so the whole system is water tight.

My ponds, circulating and not can completely freeze over and the fish have been OK, but I am in 7b. You would probably still be OK further north with gold fish like me. So, again, power is not really needed.