Hmm Rogue V5 is pretty interesting with the different ID scrolls. In a way it's a buff I feel like because since there are a lot more ID scrolls around you then you aren't forced to save the precious few in the IBM version just for rings/wands. Like I was identifying potions and even weapons/armor throughout my last game because what else am I supposed to do with an identify potion scroll besides identifying potions?
So are you always supposed to run away from trolls? I could kill them with my +1, +1 two handed sword but not two in a row which is what screwed my last game from being able to get to floor 18. If trolls are that tough how are you even supposed to manage griffins/medusas/dragons/etc? I'm guessing from floor 16 you need to just start running to the stairs ASAP? This was the case in Torneko no Daibouken, the first Mystery Dungeon game in Japan that is based heavily on Rogue. Also do medusa's confuse by melee attack or is it a beam?
On the topic of beams, are the wands of fire/lightning/cold/magic missile worth using? Do they reflect like Ice Monster ice beams in the Epyx version?
I would say it's way more valuable to have Scroll of Identify. There's just not much value in identifying potions, scrolls, armor, and weapons most of the time because they are so easily use-ID'd. Of course that can get you into trouble or waste it, but that's worth it compared to the value of identifying game-changing wands and rings.
No, you aren't supposed to run from Trolls. But they are definitely a benchmark of how good your chances are at going any further. I definitely use my wands and other "get out of jail free cards" if I don't have a two-handed sword. +1, +1 is pretty good, but you're right, at about Depth 14 is where you need to start pumping it up with anything - enchants, xp levels, improve your STR, etc.
Yes, at some point it's time to run, and that point is 17. That's where Medusae start to appear. I don't know what you call it, but they can confuse you if you can see them I think is the rule I go by. There's some way to get next to them without getting confused, but I don't understand exactly how that works. Even if you duck into a room, then back into the hallway, they can confuse you the moment they step in. But at least with each move you'll either be moving away from them or attacking them.
From my experience, magic missile is pretty weak, but like a lot of projectiles, I assume your xp level and especially your STR can affect it(?) I just use up the charges on whatever I'd use arrows against. I'm not sure where you're playing, but on rlgallery.org elwin fixed the elemental wands and now they actually do good damage (as was intended) when they hit. I think there are very few instances where monsters are protected against an element. You named one and the other might be Dragons vs fire.