You just need to know what the raidus restrictions on your equipment is. Scale length passenger cars can negotiate a 24 inch minamum radiuse. if you dont care about looks you can cut that down to 22Shorty cars or 72 footers can negotiate 18"
minimum radiuse. Since they dont look good anyway to their comprosided length. the overhang wont be a problem visually.
Easments are changing the radius of the curve as it is being drawn. You do this when you draw and oval.
As for the last one. You need to know alot of variables. Stuff like. How long is my largest rolling stock and whats it minimum radiuse. what type of operation am I looking for. Am I running brach line, Mainline or secondary rout? All of these are determinants of what is considered in the track planning process.
On a final note?
Did you ever get the track plans I did for you?
James