RTO = Road Transport Organization.
Essentially people who are in charge of making the rules and regulations for traffic in each state. I think financial incentives are given to officials who come up with uniquely stupid rules (such as no roof luggage racks on private cars, allowed in case of taxies of the same make - Gujarat), so there are always surprises.
Mapmyindia has fairly accurate maps , IMO better than CN or satguide, Good directions can be had at the local taxi stand or at any local business. But they are not as good as the GPS for getting you back to your hotel in town. Most of the small towns have been mapped. You'd benefit entering the places you want to go to/stay at beforehand as waypoints and using the unit to help navigate the last few kilometres.