Does Bone Shield stack with Earth Shield? If so can I see a screenshot?
Yes and yes.
There's been an idea going around about using a large group of Death Knights to continuously use "Death Grip" to lock players and keep them from running. Does this work?
I'm not able to convince enough Death Knights to try out this silly little trick, but it could work in theory. Death Grip is currently of the Physical school and does not suffer diminishing returns. It's like having several Warriors alternating Hamstring for a permanent snare, except more evil.
What's with the presences and auras? Do they count separately? Stack? Passive?
As of the current build, presences and auras are no longer connected (e.g., you no longer have to have Blood Presence up to have Blood Aura) and thus count separately. However, neither presences nor auras currently display as buffs (unlike Paladin or Hunter auras) which can be a little confusing, although Blood Aura has the Death Knight emanate an inappropriate green gassy mist [EDIT: Discograndpa correctly points out that this is a bug from the Bloodworms talent, and not Blood Aura. Thanks for the correction!]. Presences and auras stack and are passive effects.
How do the new warlocks feel in pvp? Our main ability of survival was our stamina and +20% extra healing from our fel armor. Now that we will be sharing gear with priests and mages and get more spirit and less stam, are we underpowered in survival?
This is a good question that's difficult to answer. The best representation of PvP would be at Level 80, but right now there just aren't enough Level 80s to test this. Furthermore, itemization for Wrath of the Lich King is far from finalized, so we may or may not see Stamina-heavy cloth. At any rate, Koraa recently said that "considerable work" will be done on Warlocks before Patch 3.0, so it's too early to give anything conclusive.
It's important to note, however, that Soul Link is now just 11 points into Demonology, and although Demonic Embrace's numbers were nerfed, the Spirit penalty was removed. This means that PvP-oriented Warlocks might want to pick up some talents in Demonology and there's a possibility that Spirit might actually become a useful stat for Warlocks. We'll have to wait for Blizzard to make another pass at Warlocks and see what happens.
This is a question I've always wondered, does Beacon of Light attribute threat to the paladin or its target? And also with Divine Guardian, does it turn Divine Shield into an absorption bubble like some think it mentions, or how does that work, exactly?
As mentioned in several articles before, threat from Beacon of Light is generated by its target as it is applied as a buff. Divine Guardian does not turn Divine Shield into an absorption, rather, all damage sloughs off the immunity. You should see the following message in the combat log: "<raid member name>'s Divine Guardian deals 0 damage to <your name>." Essentially, it becomes a 30% damage reduction for the raid for the duration of the spell.
One of the major complaints about TBC is the lack of uniqueness in the design of armor sets. For example, in TBC, PvP and PvE sets share the same models, even going as far as different classes sharing the same armor models (S4 anyone?). Has Blizzard addressed this in the WOTLK beta? Personally, I would love it if Horde and Alliance had their own unique armor, similar to the way it was in pre-TBC.
This isn't answered in the Beta, where armor models haven't been implemented (e.g. the PvP sets use Season 4 skins). However, Blizzard has stated on multiple occasions that PvP and PvE gear will look distinctively different from each other in Wrath of the Lich King, so I wouldn't worry too much about that. On the other hand, because classes will now share the same itemization (e.g. Warriors, Death Knights, and Ret. Paladins), we might see homogenous armor sets between classes -- so that's a concern. They have not expressed if Horde and Alliance will have different armor sets.
That's all for today! Keep those questions coming. Please note that if your question hasn't been answered here, it's because 1) it has a good answer from one of our readers in the comments, and 2) we might not have the best answer for you at the moment. We'll try to cover all the questions that we humanly can every day.