Obie,
You can either turn the AI for your party members off and control them manually, or you can customize it to how you want them to behave during the fight. To control them manually you click on either your party member or their portrait on the left, and can then tell them to do something (attack, use a Talent, etc.) as if they were your own character.
As far as which weapon sets to go with, it really sort of depends on how you intend to use your character in a fight:
Two-handed weapons cause massive damage with each hit, but are VERY slow (actually, greatswords ESPECIALLY are TOO slow. Stupid D&D mentality.... I'm irritated by the lack of a fast but less damaging 2H option like a TRUE longsword or even a reasonably accurate greatsword). Many of their abilities are what's called "Crowd Control," in that there's a lot of knock-down and stun techniques, and abilities that "De-Buff" a target (think opposite of a power-up: They temporarily reduce the target's attack ability, armor rating, etc). You also have two more powerful attacks (Crit Strike and Mighty Blow) which have a chance to shatter frozen or petrified enemies, which can make some fights a LOT easier. All 2H talents are based on STR so you want to focus most of your stats here on level up (once again, I don't like how DA:O handles 2H weapons at all....) You're going to be using a LOT of your special abilities with a 2H warrior, so you either want to sink a couple points into Willpower, or go with lighter armor than what you would with sword and shield.
Sword and Shield is essentially your tank: Their purpose is to get the enemy's attention and absorb damage. To that end, while there's four offensive abilities, most of the shield talents improve your defense by reducing/eliminating your flanking zone, (the area on your character susceptible to back-stab attacks) increasing your missile defense, general defense buffs, protecting against knock-down's, etc. Load them up with the heaviest armor you can find and use them to get the attention of the enemy. Some shield talents require moderate DEX so you need to be sure to put some points here, however you also want high STR so you can equip the heaviest armor possible.
Dual-wield is pure DPS (personally, dual-wield is almost ALWAYS over-powered above what it SHOULD be). Most of its talents are intended to deliver a ton of damage as fast as possible. High DEX is advisable here. Keep in mind that the AI by default targets opponents wearing the heaviest armor and inflicting the highest DPS, so it's REALLY easy for a Dual-wield to get the attention of enemies in a fight with how fast you cause damage (mages can have that same problem. High-damage area of effect spells can get an ENTIRE enemy mob chasing your mage around oblivious to your melee characters whacking away at them). Because most of your stat increases are probably going to DEX to keep up with the talents you MAY not have the armor to take the punishment.
It's REALLY hard to make a primary archer character because at SOME point you're going to end up in melee range, and almost all your archery talents are very slow to execute. Which is fine by me, because the "Melee Archer" prevalent in RPGs is absolute RUBBISH. I HATE seeing that in games. Instead I use it as a secondary weapon whenever I can't, (because of a lingering AoE spell) or don't want, to close against certain enemies (archers are VERY effective against Flemeth, Gaxkang if you have a tank to aggro them while your archers hammer away, and the Brood Mother if you pick the right spot to fight her). There's some pretty useful talents, though. Pinning Shot and Splinter Shot can make for good crowd control, and hitting a frozen or petrified enemy with Critical Shot or Arrow of Slaying has a chance of shattering them which can make some tough enemies a LOT easier to deal with. Archery talents and the bows require moderate to high DEX, so you may not have the stats to use the heavier armor if you plan on focusing on all the archery talents.
