Action Vault have posted part 2 of their Firewarrior Interview with Executive Producer James Brooksby and Lead Designer David Millard:
Action Vault: Is there any form of character progression? Does Kais gain access to better weapons or equipment as the game progresses? Does the player ever control any NPC companions or party members?
James Brooksby: The player character has an advancement system of sorts in that as the game progresses, he is issued with a Tau weapon upgrade between some missions. The two-gun mechanism works by having a primary and secondary slot. The secondary slot can always be changed with whatever the player wants to swap with or finds at the feet of a dead enemy. The primary slot is given and cannot be dropped or swapped. The primary weapon is always a Tau weapon. At first, it is a simple rifle-like weapon, then a fast-firing carbine with a grenade launcher, and then on to a mini-gun-like weapon. Finally, the Tau weapon moves onto the all-new secret weapon of the Tau.
Kais does run through many missions with allied Tau Fire Warriors who have their own orders and objectives, and sadly their own fates too. Sometimes, they take part in scripted events, and sometimes they are under AI control and can change the outcome of the fight you are in dramatically as long as you protect their backs too.