There are 420 layers from what I remember I don't use many cause I don't want clutter. For example there are a lot of layers related to fishing, I don't need those so I never use them. There are hunt research layers/info that's an extra 10 bucks a year, but I can get the same info on the DFG website so I don't subscribe to those. I use the Basemap Pro because you get unlimited offline maps and it has everything I could want, plus things I personally won't use.
I think it is pretty easy and straightforward to use, but they do have a few tutorials on Youtube. The main thing is to just use it, in your yard, at the store, on a walk that way you practice making markers, recording tracks etc. When I first got it I had some questions and they returned email inquiries quickly, within a couple hours.