2. It's not necessary to draw curves following the vehicle driving track / swept path. You can think of how it works at intersections, where the round street corner radius isn't represented directly.  So the lane doesn't need to be followed according to the marked line, and the inner side. Drawing straight according to the outer side is the best from experience. This is specially the case for such roundabouts that would leave extremely short segments from an entry to the next exit. 