Copper dosing in a LFS

[fishboss825]

Okay, as many of you know its pretty hard to get a unanimous answer about anything in this hobby so forums can be a confusing place with everyone contradicting one another, so instead of looking for my specific answer I'd rather just ask a specific question. I am in the process if starting a LFS we are a very small location (more of a dream really) that was created in a basement, with very limited cash, and time as my partner and I both work to pay our bills. The last 8 or 9 months have been pretty crazy but we have managed to set up a decent location for what we had to go through to do it, now for my question, we are trying to sell high quality animals here, mainly because there is only a Petco in my area to compete with and the ich there could be sold by the pound, we want one of our tank systems to run with copper, being that the fish will (hopefully) only be in the tank for a week or two they shouldn't be too negatively affected by the copper. I need to know:
What brand and type of copper should I be using
How much should I be dosing and when to keep the system functional
Should I under dose?
Will this greatly effect my bio filter?
What is the best copper test kit?
What fish absolutely do not tolerate copper? I've herd fish with skin don't do well but I've seen puffers and eels (expensive ones) in copper systems at other stores.
I'd love to hear from someone with a shop that's already doing this and how their success has been, but anyone running long term copper could help.