There's a difference between the OOC "I use Twin Strike on those goblins." and the IC "I fire a pair of arrows at the goblins in the back." OOC you ask who needs healing, IC you just heal. The concept I believe is that the characters know their own abilities and those of their allies so well that they can interpret what each other needs, and they see things that we don't, while at the same time only the players are aware of the system rules. Talking is a free action, and as such can happen any time, but if you interrupt another player's turn with a ton of dialogue that's rude, and slows the game down.