Pete Thornton· Premium Member
Main line or mains is good. The side track is a siding.loops be called, mains
Few g gauge locos exceed 2 amps, so check the output of your power pack. On a small layout like that you can't really load them up with a heavy 20 car train.
The track may move and the corners take strain from the moving loco. If the track is screwed or clamped together you shouldn't need to screw it down. If you are using regular push-in joiners, I'd suggest some brass or other non-rust screws on the outside of the curves at the corners. Not through the ties, as you have expansion/contraction to worry about.