Nice Job Wubsie.

I've been working on my frost DKs a bit as welll. I've given them any frost and extra shadow relics I've come across. I only have 13-14 traits invested into frost. I mainly go 4x frost + holy for LFR it makes the fights go faster than all tank. Frost has had some very nice buffs but I still think blizzard needs to fix their mastery scaling instead of buffing obliterate to keep the spec competitive.

I made a few frost dk GnomeSequencers. A useful one is to to spend runic power on death strike instead of frost strike if they need some extra healing. Frost has some very good RP gain so you can actually do pretty decent healing but it does cripple your damage a bit.

I'm at 32 traits with my blood spec so once I get that first trait @ 34 for the 10% armor I'll probably start investing points into frost and holy.

Frost speeds up regular mythic clears for artifact power each week its also nice to have an AoE stun on a short CD but sometimes I still stay all tank just so I can ignore mechanics.

I would have made your team be all blood elves instead of undead. You are missing out on the glory that is arcane torrent!

For the healer for a trinity setup I would think druid healer or holy priest would work better than shaman or pally healer. If I was committed to a trinity setup I'd drop my pally for a druid. The extra b-rez can't hurt and at least they can do nearly all of their healing on the move since any fight with ranged mechanics would make your healer move often.