Tank: Prot Paladin
If your Blood DK won't sit then you'd probably have to 2-tank it - which I think is a waste. You could probably swap the Shadow Priest in for something - we don't have one so I'm not too familiar with them.
Log of our first kill with almost the exact same setup (We had a Holy Paladin instead of a 2nd Resto Druid and a Brewmaster instead of a Prot Paladin)
Three healers is doable but I think that 4 is definitely superior - especially for learning. It will also be easier to push stacks to 28/29 in each screech phase so you can make sure you have 3 minute rotations - which will be easier to repeat. It also helps a lot with dispels and keeping people topped in the kite phases where people can end up pretty spread out.