There's an elevation slider in the road tool. But for that, you're probably only going to need to change them + or - .05 or .10m
The slant slider might help as well.
To get the best alignment, you might try using 4 waypoints close together, 2 for each road, with the waypoints for a road aligning with the 2 sides/edges of the opposite road. But that's generally overdoing it. You could probably just have 1 waypoint for each road placed on top of eachother.
To insert a new waypoint, select a segment and press Insert to make a new waypoint in the middle of that selected segment.
