Correct. And the new barrier spells actually work better in a sense, as you can get other abilities that synergize with them. A mage investing in ice magic can pick up a particularly useful passive upgrade that causes your barrier to burst and freeze nearby enemies when it goes down, for instance, or a fire mage could pick one that causes every spell they cast to drain half of their current barrier to increase its damage.
I think that's fair. Although DA2 isn't actually more action-y in any mechanical sense, just faster-paced and with better animations.
Right. The only wave-based fights are the Fade Rifts, which spawn demons once as you approach them, then again after the first group dies. And there's a couple of areas where undead will rise up out of the ground, but only a couple.