Seriously, you can play what ever you prefer,
Yes it might be squishy but you if you can play with decent people there' no problem.
I don't know of any DK's who play Unholy so have no idea how it would work out for you.
Vengeance removed, but you can still pretty much 1 shot rogues and take down mage's but a 1 button spec can't be to fun =<
Okay so there's a thread in this forum somewhere that has a list of gear sets for each different class / spec i'm not sure if they are accurate though, ill made you this one, you can choose to use it or you can choose to use the other.
chardev 9
I'm not sure how close to best in slot that is without using GF'd items I just like spending time on chardev it might be an idea to take BS instead of engineering though as synapse will only give 42 of the chosen stat in MoP and tazik will only hit for 1.5k critting for 2.5-3k
Try asking Satina or Kicts they are two good dks I know of.