Draw your centerline, split the cork roadbed and apply it one side at a time against your drawn line. Using easements into the curves will help both the looks and operations. Tack the track down, but not too tightly. If you tack the track down too tightly you will deform the ties and tighten the gauge, which will cause you operational problems (derailing and such, especially in curves). If you ballast the track the tacks can be removed after the glue dries.

Acceptable radii is going to be in large part dependent on what locos and rolling stock you use. 40 foot cars and four axle diesels can negotiate tighter curves than 85 foot cars and six axle diesels or large steam locos, but to be on the safe side always go as big as possible with your curves. That way when you get that great new engine or car you won’t have to worry about being able to run it.

I’ll have to leave DCC for those who use it, but the basics are always the same. DCC is just less forgiving of errors than DC.