[David]

I'm sure someone more qualified than me will chime in but I've always used black pipe for gas. Certainly can't use copper due to chemical reaction.

What do they mean by T'd at the meter? Wouldn't any T's be inside the house? so there's only one line from the meter entering the house?

There are charts for gas flow per pipe size and you should have the BTU's per device so you can calculate the required pipe size.