Questions on new frame rails

[bhaagjr]

I am working on a new King Hauler that I would like to do some modifications to. I bought a set of frame rails and air ride kits from TRUESCALE. I have a couple of questions from the experts out there.
1. What size drill bit are you using for the 3mm threaded holes?
2. What is the best way to drill the rails. Do you secure them together and drill the holes in both rails at the same time?
3. When you start building the truck do you start with the front suspension and work to the rear, drilling and mounting the accessories as you go?
THANKS FOR THE HELP...Buddy