Werewolves can't even use items or spells. The only way to use either is to use one with a duration then transform. An example drinking a Fortify health potion or casting Frost Cloak. All weapons and apparel are unequipped.
1) Enchanted arrows that have those effects would make more sense than a ring that causes your arrows to have them.
2) Werewolves as stated above don't use items or spells. The ring of Hircine is as useful as it gets and it simply lets you have infinite transformations, but doesn't do anything for you during a transformation. Only blessings would actually work.
3) Agreed, the vampiric drain is a worse version of the Flames spell with the only edge being Absorb health. It actually doesn't work on automatons, random fact.
4) Indeed, but heavy armor gauntlets preferably.