So yeah, the original intent is that the world is open to them and they can see the map and decide where to go. Forbidden Lands is very much designed around maximizing player agency in a sandbox. That being said, they don't know what's "in" that map. While generally the idea is that the marked villages, castles, and dungeons are adventure sites of that type they have no idea what they'll find when they get there. They may have some idea through legends or rumors but that's really it.
As for travelling 80km in a day. It's absolutely possible but my players haven't done it yet. You can travel two quarter days through open terrain just fine so that's around a maximum of 40km. If you want to add a third quarter day then you probably run into the problem of light if it's not summer but even then you still have to make a forced march check. Lastly, you can travel the fourth quarter day but that requires an even more difficult forced march check and you're definitely in the dark which complicates things more. So yeah, possible, but it'll be a memorable event if they pull it off. And we're not even mentioning that characters will fail pathfinder checks semi-routinely which can lead to all sorts of wandering shenanigans or running into random encounters, etc.
EDIT: There are talents that could allow, probably just an individual character, to perform some absolutely heroic travel distances in a day. But that's like Gandalf and Shadowfax kind of stuff and would seem incredibly dangerous unless you have a small party of Aslene Way of the Steppe Riders.