Dk turning into a great support class but a lot of the best support you can gives requires a mag build so your insistence on using the bow creates restrictions. However restrictions breed creativity so...

I would run sword and board as you second if your going to support a group and try and control the fight and take the heat off ally's similar to a over tank.

S&B bar - defences and cc
Ransack - cheap stamina based skill that debuffs armour
Invasion - gap closer keeps you near dangerous targets provides a stun
Vigor - stamina based heal gives you and your team a decent HoT
Caltrops - large aoe that snared enemies and pulls from stealth
Igneous shield - group shield that buffs heals. Use before vigorous for better ticks
[ult] magma shell - large group shield could be decent panic button

Bow bar - buffs, dots and single target
Lethal arrow - ranged single target high damage healing debuff
Venom arrow - ranged dot and this morph interrupts casters use it on someone spamming frags at your team
Bombard - aoe root to keep people in place
Igneous weapons - 30 second group wide damage buff
Flex slot - can be anything depending on situation
[ult] take flight - hard hitting physical ultimate

The flex slot could be anything from rapid maneuver for group speed buff to the flappy wings cos... Well flappy wings

Your race choice isn't the most synergistic with the play style though as the stealthy perk doesn't add a lot to your build (your with a group not trying to stealth snipe a target)

You may want to look at redguard (high sustain and decent damage) or Orc (hard to kill thanks to health regen and decent melee damage)