These tracks should be compatible with most brands. I have tested most pieces, but not all. So if you have any problems please drop me a comment.
One quick tip: if you're printing a piece with both a road and a rail side, print it rail side down to save on support material.

Doesn't Matter

Yes

All the CAD work was done in FreeCAD
All the math behind the CAD was found here: http://tamivox.org/dave/train/index.html ,more specifically the 36 degree system described there.