2. There are many avenues for crafting special ammo besides essences, which I believe is what you're eluding to.
3. If I'm not mistaken, hitting an enemy with a special arrow inflicts piercing damage and the special arrow effect. At least I know it is this way with some special arrows.
4. Perception helps with accuracy.
5. I would think a flaming arrow, or one dripping with poison, would do more to the bow itself than a normal arrow.
As for the archery "class" as a whole, I haven't played a dedicated archer so I can't comment. But I do know the enemy archers are a huge pain sometimes.
Edit: I would say, though, that if archer do lack DPTurn, they make up for it in utility and versatility.
