one guy did all the voices for the player dwarfs, namely Javier O'Niel, who is a 3d artist for videogames (and not part of ghost ship games as far as I know, prolly a friend of the devs or something similar), not a voice actor. the different dwarfs all use the same voicelines (except for a few class specific, like when you select a class or land with the droppod), only they are digitally pitch-shifted to different levels (if you listen closely to some of the voicelines, esp longer ones, you can hear that they are the same only edited)
the only other voicelines in the game are delivered by mission control, who is voiced by Robert Friis, art director and Co-founder of ghost ship games. also mission control looks very much like him too, so its basicly a self insert.