You will find that for the most part, very little terrain that you will want to ride is on private property. Some areas will occasionally have day-use fees but I find that even that is rare. Typically, this isn't much of a concern when looking for new spots. However, you want to research the area beforehand and make sure you don't need any permits. For example, from my home resort of Arizona Snowbowl, you can access the backcountry from the ski area with a free permit. However, if you access the same backcountry using other routes, the permit is not required. These permits also control parking in certain areas, which is something that you want to look into as well. If you have good topo maps and knowledge of areas, and know you have permissions, there really isn't much of a limit what you can ride, which is the beauty of backcountry riding (this of course assuming you have proper gear, knowledge, and certification to travel in avalanche terrain). My trusted backcountry partner and I have a new hobby of leaving for a few days and literally just driving to areas and cruising around until we find something we want to hit. Then we skin up and bag the line. However, we both have avy 1 certs (taking avy 2 this season), gear (and experience using it), and years of backcountry riding behind us that gives us confidence to do that. Hands down, the best way to get into backcountry riding is to find someone with a good amount of experience and get them to take you out.
As for heli-operations, the ones I know of have contracts for certain areas. These areas very quite a bit in terms of size, but all heli ops are restricted in this way. If you want to ride the best and least tracked lines, skip the heli trip and get a splitboard.