Jtandme,
First, welcome to the forums.
There are several reputable and reliable brands of n scale track available. While choosing a brand you also need to consider what code (height of rails) you want to use. Some manufacturers offer more than one size, others don't. Kato has Unitrack which incorporates plastic roadbed into the pieces which makes installation easier but is more limiting in configuration.
I am not familiar with copper track but I think it would tarnish (oxidize) impairing electircal conductivity. Stick with nickle silver.
Good luck!
Yes, nickel-silver track is the only way to go. You are probably thinking of old brass track, which is copper colored. I don't think anyone makes that anymore. Brass tarnishes and must be cleaned more often than nickel-silver. The oxide of brass is non-conductive, so trains won't run, while the oxide of nickel-silver will conduct electricity.
All tracks need to be kept clean, but it's much less critical than nickel-silver.
It takes an iron man to play with a toy iron horse.