I don't think you can really do the former, most mobs are positioned in a way they'll see you, or have triggers that alert them to your presence. In fact the stealthy stuff is more useful for just attracting less attention and making enemies more manageable on your terms.
Ranged is... sort of. I don't think it's as potent as in Demon's Souls though, but you can lock on at least. They get too close though and you'll definitely have to fall back on other methods except maybe if you can perpetually keep your distance.
Heavy armor can be very situational, some enemies are just a pain without better mobility and will tear apart your poise anyway. Still, it's a good idea period to get something like 40 END, so keeping some on hand seems to be something of a "why not?" proposition, especially without Demon's Souls's item burden.
Unless they release an updated version I'd say avoid. Patches have changed a significant amount versus launch, and the DLC stuff wouldn't be factored in. And some people REALLY seem to hate it, though I thought it was pretty useful.