In nwn 1 & 2 are arcane archers any good?

They're pretty much the only viable option for a ranged character. Your issues is arrows. You go through so many that you have to constantly buy more. That can be a pain, but otherwise Arcane Archers are pretty good once you get the bonuses kicking in.

I just recently completed SOU and HOTU with a Ranger (for the first couple of lvls) who turned into an Arcane Archer. My guy was pretty darn good up until I'd say chapter 3. After that he really just couldn't pump out a lot of dmg, however he did always hit his target and could kite an enemy to death if need be (the end boss of HOTU was such an instance) since he had a good build and what not. So if you want a toon that great throughout the game till the final chapter...play an arcane archer. In the final chapter, hes only "good" not "great", the arrow of death pretty much never kills whatever you target with and the fire arrow while great at the start is pretty much useless against most enemies by then. Lastly, the seek arrows do not fare much better either near the end of your play through

I haven't really tested an Arcane Archer to see if there any good in NWN2 so I can't help you there ( I made one long ago for SOZ when it came out but honestly I cannot remember if he was any good)

I got some things to say

-How do you kite in NWN1+2? you cannot move and attac at the same time.
All I can think of is using spells like entangle. But your spell DC will be
pathetic since AA does not have spell progression.

-An archer might be very useful in SoZ.
I play it right now and in most encounters you are on one side and the enemy comes from the other side.
If you have 2 melee fighters the rest of your group can attac from the distance.
In the OC it happens more often that many enemies come from different sides and most of your chars cannot avoid melee combat. But then you can give him a melee weapon. He will have some HP and an everage AB.

-After a short search I found the best archer to be:
http://nwn2db.com/build/?125010
But you must have 11 charisma
Many attacs per round, fire several arrows at once, use enchanted arrows, sneak attac damage and you can stunn your enemies when fireing out of stealth.

NWN2 OC, or SoZ doing a bard/ranger/Arcane Archer would seem a decent choice.
In OC, that'd mean you can do the bard stuff and ignore Grobnard, which is a boon.

Don't remember if there's anything for bards in SoZ, but a ranger is always handy as the party leader/guide.
An archer-ranger would benefit from AA classes in a big way.

But continuing from OC to MotB, I'd imagine any kind of archer would be at great disadvantage.
You could put major elemental damage enchancements in melee weapons, but not to ranged. But you actually can fire, then run away until you're ready to fire again.
Preparing to fire isn't actually disrupted by movement, for whatever reason.

Works at least in NWN1.

I was able to kite some mobs since In NWN1 since my guy was permanently hasted. You simply fire once then run away. Rinse and repeat. The mob should never catch up with you if you know what you are doing. However...if they have magic or ranged weapons, obviously kiting won't be that effective as it would be with a melee opponent.

I beat the SoZ boss by kiting him. Opened by casting extended haste on my part, then had the Ranger draw aggro on the big nasty brute of a boss while the fighter/rogue and fighter/RDD rushed past to deal with the squishy casters. Party Sorcerer tried to keep aggro against the big nasty caster so his spells would harmlessly bounce off his spell mantle. Once the casters were dealt with, everyone pulled out a ranged weapon and just started playing Monkey in the middle with the melee boss, who was too slow to keep up with the hasted party. Because my party caster was a sorcerer, I could just keep casting haste all day.

Very memorable fight since I was so grossly under-leveled (only a level 14 party - that fight is intended for level 18-20's)

Is there any aggro system in NWN1+2?
I have the feeling everyone attacs the first thing they see.
Only when there are several of my chars in melee range and one of them
runs away the enemy mostly attacs the other one after some seconds. (in SoZ, I play this now)

PS: I don´t think I will be underleveled.
I explored the entire map before going to the sword coast and now I am lv9-10.
I just arrived at crossroad keep for the first time.

Taunt skill. Calls a single opponent to melee attack you.

This is the description of taunt:
---------
Taunt is used to provoke an enemy into dropping his guard for a short time. At higher ranks, multiple enemies can be affected.

Check: The enemy must make a Will save against a DC equal to 5 + the attacker's Taunt skill or suffer -2 to AC and -2 to Concentration for five rounds.
------------
It lowers AC and concentration.
Nothing is written about the target attacs the person who uses this skill.
In another forum on gog (to lazy to search now) somebody said, taunt does NOT force the target to
attac the skill user just because a skill with this name does it in many other games.

On the other hand, there are lots of things not written in the manual.
I was surprised that I got the exotic weapon profiency when my cleric/paladin became a doomguide.
I like to test it but in my group (SoZ) nobody has this skill because I never used it in the OC/MotB

Strange.
I was sure of what I was saying, but I guess I might be confusing this with some other game.
It's been a while and I'm not sure I ever used the skill myself.

The description is correct. The use of the skill does not force the opponent to attack you (but they usually will because you have to get right up in the opponent's face to Taunt them). Taunt can be used quite effectively in NWN1, but I'm not sure about NWN2 as I never used it much there (just a quick test in a test module, if memory serves). Just be aware that when you Taunt, your character is flat-footed which may or may not be an issue, depending on your character build.

I wasn't so much speaking of forcing enemies to attack my characters, so much as using placement and timing to achieve that result against the AI.

They were, but I think it was the move from D&D 3.0 rules to 3.5 that did it. Out of their hands.