I don't have a magic number of minutes when running back to camp becomes "too much." I would say at least an hour would be nice.
For lowering difficulty, I've played on casual before and still had to fast travel back to camp more than I thought was fun. Casual setting shouldn't be automatic win, but it should decrease the need for restocking considerably.
Having never tried Casual, I really shouldn't speculate about how easy it is to avoid damage.
Wouldn't an hour be pretty close to "forever" in practice? After an hour I've typically either reached a new camp, or exhausted my current direction of travel and need to return to base and start in a different direction anyway, or wanted to turn in some SQs for the XP and fast travelled back to do it, or I'm coming up on the loot limit.
I suppose my experience might not be typical, though -- I only had to return to base for healing maybe six times in my first game, IIRC. We could look at LP videos, but I have no idea if those represent a typical experience
I think I noticed it in the game because 95% of the game we're in a wilderness zone with respawning enemies. There is no Denerim market, no daytime Kirkwall, no Redcliffe village pre- and post-zombie apocalypse. There's VR, which after the first visit there's not really a reason to visit, and Haven/Skyhold. So the majority of the game has me walking through combat zones, because even if I've cleared a map, when I go back there are more enemies to fight (who don't give me experience any more).
Well, VR does have a couple of good shops. Though the really useful one sells schematics.
How does healing come up in the areas you've outlevelled? Surely you're not taking damage there?
In my experience, setting something to preferred didn't work very well. I didn't notice anyone actually using a preferred ability more often than just auto attacking or another ability.
Probably a problem with the preferred abilities needing too much stamina or mana to fire at the moment. This can be an issue when cheap abilities like Block and Slash or Whirlwind are available. Even if not preferred, if they're off cooldown they will fire before there's enough stamina to do another War Cry or Challenge. Then that's 10 more points gone which need to be built up again before the Threat-management abilities can be used.