As for the pump, don't buy a little "pond pump" unless that sucker is at least 1/3HP. Get a "submersible pump" with at least that rating. If you cannot get the velocity of flow through your chiller, you are not using the whole chiller capacity. It can make a big difference, especially when you have had the opportunity to use the proper setup.
From experience: do your homework on a pond pump. Its a great tool to have (I use one for chilling as well), but most are not built to last.
Lowes.com has customer reviews for all of their brands. Most reviews will point out that the pump lasts 6-12 months before giving out. Pick up the one that has a reputation for a longer lifetime. Price point doesn't necessarily reflect quality, either.
Most pond pumps are rated by Gallons Per Hour (GPH) rather than HP. Some models don't even give HP with their specs. I think I bought a 560 GPH model, and it provided plenty of flow through my 3/4" IC.
IMO: Copper ain't no big thang on the brewhouse side.