As I was playing BG 2 and after having refreshed my 3rd edition rules for the upcoming release of IWD 2 I asked myself some things and thought I'd ask it here too in case anyone knows. First of all will there be attacks of opportunity? In a real time game it could get really complicated but then again they are there for a reason. Also I remember spending a whole afternoon doing stats and stuff like that and in the end I came to the conclusion that using a two handed weapon deals more damage than dual wielding but only if they keep the rule where you add one and a half your strength modifier, are they gonna use that? Also how about readied actions, how will that be implemented , and if they don't use that then how will you be able to disrupt a mages spells, especially if there are no attacks of opportunity (which I'm guessing there won't) Finally what happens with counterspells? will you be able to counterspell? Well that's pretty much it, by the way it's a shame they didn't use item creation feats and prestige classes , maybe they should give you access to prestige classes as rewards but , oh well c'est la vie.
buh buh

Don't know much about 3rd edition D&D, but Black Isle has said that they will use as many of the rules as possible. At least a few of those things you said (like the dual wielding vs two handed) doesn't sound like something impossible to have in the game.

For prestige classes - it was designers' decision because everyone is already sick of drooling over BG2 kits.
Besides, what would prestige classes be? Zenmaster perhaps? Valkyrie? Come on!

The spell disruption currently is set to work like this:
by J.E. Sawyer - IWD2 lead designer

When a caster takes an amount of damage over 0, there is a chance that the caster's spellcasting for the round will be disrupted. Use the following formula on each ROUND in which the character takes damage.

The spell disruption difficulty is defined in this manner:

* 10 + Spell Level - Caster Level/2 (round down) - Constitution /2 (round down) -5

spell disruption roll is defined in this manner

* Random 1-20.

If spell disruption roll >= spell disruption difficulty, the spell is cast successfully. Otherwise, YOU BLEW IT.
Note that also is planned to add the Concentration skill that prevents the disruption of spellcasting.

I don't know what is "readied" actions.

For two-weapon style, currently there is ambidexterity feat that lowers penalties for two-weapon fighting. How does it actually work, we'll have to check within the game, right?

I assume by 'readied' action you are refering to drawing a weapon or using an item. I would say that IWD2 will not use pause when you check your inventory thus the enemy gets attacks as you change things around on that screen. AoO are not really used in a real time game. They could give character a free hit for AoO but there is no difference between running and walking or full or partial actions. It's more fluid turn base combat thus many of the issues surrounding AoO don't come into play.

Actually no, readied actions if (and this is a not so accurate explaination cause I haven't played it in a while) is not playing when your initiative comes but instead holding your action so you can perform a standard action when an event occurs, me and my friends mainly used this to either guard doors (something like if I see anyone coming in I shoot him) or counterspelling and disrupting spells (when that mage casts a spell I fire an arrow at him) and things like that