Yes, dialogue is better than debate as a way of resolving differences and coming to a consensus, because dialogue takes into account everyone's opinion. With a dialogue, there needs to be a consensus before taking action. If everyone agrees with the action, they will be more likely to actually follow up on the terms of the agreement.
No debate is better form of discourse than dialogue. I believe that debate is a better form of discourse because it is more controlled while both sides are able to give their sides. There is more room for argument becoming out of hand during dialogue because it is not as controlled so each side gets equal time.