In addition to Stabbey's answers:
1. Exactly, yes. Some of this can be mitigated by taking Loremaster 5 and having access to all elements, but sometimes you will need weapon damage.
2. Yes, they do. As Stabbey says, they sometimes don't get treated as such by the game.
3. VERY useful in my oppinion. In fact, I'd prefer an Archer to a Rogue any time, even though you cannot backstab with a bow (you can do guerilla damage with high sneaking though, and you don't have to move in position). Special arrows make the build versatile. Besides, you need at least one character with high Perception anyway.
I'd prioritize bows, even though it might seem that crossbows get a better damage per AP at first. It's not easy to fit 6-7 AP into a turn multiple times. Besides, with Quickdraw bows will catch up.
If you want a specialized archer, make sure you look into Crafting. Self-made bows are the best.
4. You can easily make a Rogue / Archer hybrid given that you'd want to max Dexterity for both. Note that changing weapons in combat uses up AP. So maybe start shooting first, then change to dagger and go melee?
