Andy hit the nail on the head. I built 45, 90 & 315 degree's in each version and still have over 220 some crossings on the DLS. If I was to build them in more degree's, they would multiply exponentially. As far as the roll of the crossings, they can be rolled to match the slope of the ground by holding down the shift key while rotating them. Usually 1 degree is enough unless you're building a roller coaster.
Even in the real world, the railroads don't build the lines to accommodate the roads. The highway department has to first request that a crossing be installed and then the road department has to modify the road, if need be, to use the crossing.