On that note, I tested TBC questing vs WotLK questing under the new scaling with 7.3.5 back when it first launched. Interestingly enough, WotLK is nearly twice as fast, mostly due to newer quest design and world building philosophy.
I haven't actually checked, but I assumed War Mode would be available for everywhere. But now I'm wondering if it's just the new zones, or is it available from level 1?