RE: Brass rails and RF interference
Tom,
I can advise that myself and many other scale modellers down under have been using brass rails with brass inserts and had no problems with Rf interferrence at all.
My background in case you are curious is Electronic Engineering.
If you want to be really pedantic you could ties the rails to the negative rail on your battery pack to enure all is at the same potential.
good luck with your build, your posts and building add much to the forum.
cheers
Peter