Rather steep learning curve, but once you get the hang of it, Base Camp is pretty neat. I use it regularly.
As far as the POI files, check out
Extra POI Editor. Once you've downloaded the POI file from wherever, it'll do the necessary conversions for Garmin. It's also good at creating your own POI files.
Experiment with the Trip Planner function . . . and know that just because Base Camp plots a route, your GPS may change it for whatever reason. Trick to force the route is to create and use waypoints on the roads that Garmin doesn't choose to use and route to them. Once you program the start and end points of a route, use the slider to find other things along that route - including your waypoints. And you can right-click any point on the map and get a menu that lets you see what's near that point from Garmin's built-in POI files.
I always load a base camp created route into my GPS and then display it to see if it still goes where you want. That's especially important for the RV . . . if a campground publishes driving directions, it's good if the GPS will direct you over that routing, but sometimes you have to force it.
Don't give up - Base Camp is very powerful, just poorly documented. Best of all, it's free.
al
