New to "G" scale hobby

I am trying to set up a two track(side by side), I want to put it 77" above the floor in an 18’X24’ room. I will model MILWAUKEE ROAD(Branch line diesel) & NORTHERN PACIFIC (Branch line steam or diesel) 1950’s power and rolling stock.

  1. What radius would anyone recommend; 24",36" or 48" and why would you recommend it.
  2. With two side-by-side tracks, what safe distance should be maintained between each track on straight and curves maintained with each radius?
  3. What would be suggested as the easiest, best and least expensive way to secure roadbed to wall? is cork under rail suggested?
  4. What type of tranformer should be used,given the two seperate track/train operation that will be employed?.
    Any help that anyone could offer would be greatly appreciated. Send any answers to knytwyrm@aol.com