I've been mulling over a very similar idea for a little while now, only I intended to go deeper then the 2 feet to keep the water temps more stable winter and summer, and less bird (wild bird) predation on my fishes. Not sure how long the plastic would last b/c I wouldn't be able to afford the real "pond liner" stuff.
Yes you could definately raise pinkies for that, I've never looked into it to see what kind of set up and food requirements
After the shrimp are gone, 3- to 6 weeks, or you can check with the ammonia test strip. Yes, there are feeder gold fish and you will certainty putting them into a unfriendly environment. Because these fish are hardy-- should you expose them to the rigors of the ammonia cycle? Doesn't seem humane to me, it's like visiting a plant without enough oxygen--just enough to leave you gasping. If you have no added clormines in your water you will save the expense of adding a DE- clorinator, just add it at water changes or top offs, clorine dissipates after 24 hours in a open container. You can add several layers of wet newspaper under the liner for your pond, it will conform to the shape you pick and dry extremely hard, never tried carpet. Your pump will cut down on mosquito larva and add oxygen to the pond, which you lose during exteme hot weather.
