"What's the status of Rivendare's deathcharger, the Wintersaber/Venomhide, the ZG mounts, and the Argent Tourney in the beta? Has anything changed with them? I imagine there've been changes to Stratholme at least..."
I can't say what's up with the ZG, Wintersaber or Argent Tournament mounts just yet, but I know for a fact that Baron Rivendare is gone from Stratholme as of this latest beta build. Whether this means his deathcharger is gone forever still remains to be seen. He does have a replacement ...
"Speaking of goblin and worgen mounts, and whether you can get them if you're not one of those races if you reach exalted with them... Are there any plans on adding both races to the Argent Tournament? I found that an easy way to get rep with each race."
There are currently no plans to add Gilneas or Bilgewater Cartel representatives to the Argent Tournament.
"With all the new watery areas in the zones, will there be some kind of mounts or swim enhancements to get around (especially in the flooded shimmering flats) or are we expected to do tons more swimming?"
At least in Vashj'ir, you get a swim speed buff almost immediately upon entering the zone, and you also gain the ability to run on the sea floor. Later, you get a water mount that moves at 280% speed.
It's unlikely we'll see these privileges expanded to other zones, because there just isn't enough water to justify it. Vashj'ir is built from the ground up to be a very 3-D zone.
"Whatever happened to Deathwing Scar, the supposed entrance to Deepholm, 'cause making the entrance to Deepholm in the Maelstrom doesn't make sense. The Maelstrom already caused one cataclysm, its like a hole in the wall, how does Deathwing cause a new cataclysm stepping through an 'already there' hole?"
Deathwing essentially broke through the ceiling of Deepholm and busted out of an already existing vortex of chaotic energies -- that is, the Maelstrom. The only reason why you can get to Deepholm from there is because of Deathwing. The Earthen Ring is currently doing its best to keep the rift open so they can send more people down there to fix the World Pillar, which was shattered when Deathwing broke through.
"What are the languages of player worgen and goblins?"
The playable goblins are able to speak goblin and orcish. Worgen speak common and worgen. The worgen language isn't yet implemented.
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