Note that rerouting distance is a compromise. When you use offline router (like OSM Scout), you are using your own device and the main price to pay is the battery. When you use online router, all API calls by all users are summed up by the provider and if we exceed the free tier we would have to find the way to pay for it. Hence having too small rerouting distance with online routers could lead to problems. @otsaloma has a better overview and he'll let us know if we are going to hit it, I presume.
Rotating labels are possible, in theory, using tiles as well. For Mapnik, it would mean composing other projection that would flip the world. However, it would require significant time to do that properly. As mentioned by @otsaloma, an alternative is to look into vector maps. In long term, vector maps (OpenGL-based rendering) are better solution and I probably would prefer to look into that than spend too much time on hacking Mapnik projections.