Patch 2.3: Druid Changes (Source)
We are currently planning to make a Feral-focused set available in season 3.
The idea is to make this set have no plus to healing on it and be focused on Feral statistics. Things could still change though.
We are still finalizing details on PvP and PvE items, so a lot of things can still change and I don't know about new Druid specific tanking gear yet.
On a related note, for items that grant attack power in Cat, Bear, Dire Bear, and Moonkin forms, in general we are planning to increase the amount of attack power they give.
Patch 2.3: Warrior Changes (Source)
Not a lot is finalized right now, but we are currently planning to make Improved Berserker Stance provide threat reduction by 2/4/6/8/10% while in Berserker Stance.
Patch 2.3: Arena S3 Titles and Mount (Source)
We plan to use the same titles of Challenger, Rival, and Gladiator to give to players when season 2 completes. The players with titles from season 1 will have them removed and the titles will be redistributed to the people who win them at the completion of season 2.
Yes, it will be a different color Armored Nether Drake.
Patch 2.3: Arena S3 Weapons have new art and color (Source)
They won't be "released" until 2.3 goes up on the PTRs. No sneak peeks for you. I can however tell you that they do in fact have new art.
It's different colored raid weapons. So the weapons exist as raid weapons, but they'll have new colors.