do you use a grounding probe?

[mark]

Yes, a GFI breaker and receptacle do the same thing, main difference is cost (breaker $80 / recpt $15).

A breaker will protect everything hooked to it, a recptl only itself and what's hooked up down stream.

Not sure what you mean with the positive/negative. If it's a duplex receptacle, there should be a ground, a brass and sliver screw to hook to supply (black-hot, silver-neutral) and a other set of brass/silver screws for loads down stream.