1) A scroll of enchant weapon modifies the effectiveness of your weapon. A cursed one makes it worse (-1), non-cursed one better (+1) and blessed one at least as much better as a non-cursed one.
2) If you are wearing a ring of control polymorph and you polymorph (by stepping on a polymorph trap, by drinking a potion of polymorph...), you can choose what kind of monster you'll become (by typing its name). I recommend being a human. It's useful if you are in a risk to change to something you don't like. The ring of teleportation control allows you to choose where to teleport when you can (teleportation traps...).
3) Normally yes, I suppose, but intelligent wizards might have not to.
4) Did you unleash a water demon? It's extremely unlike to get a wish that way.
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