Id def use the priest/tank/lock as the 3 and let the other guy do hunter and maybe offheal with the drood or lvl up another dps.... IMO.... priest makes the best multibox healer (just so much easier on grp heals while having good single target healing too)

.. not sure if having a main healer and an offhealer in a grp would allow you the dps needed for some fights.. but it would be nice for the priest to be able to focus heal on the mt and the grp get healed by the offhealer

..if the firend was going to run 2 dps, Id suggest making another hunter since 2 of the same class is easier to deal with (least seems so in my case)

:edit: just saw the other post on 5 classes..if you are planing on pve heroics, then you more or less need to have a dedicated healer and dedicated mt (prot pally/warr drood)