I like the core concept a lot. I would think their primary stat would have to be agi, and their gear would need to be mail...this is the only obvious option based on the game's current class distribution. Clearly a lot of the monster-based abilities would need to have their names changed to fit WoW's lore a bit better...but I like the flavor of what you've come up with so far. "Glove Slap" sold it for me. I think the addition of an on-demand "reload" ability (with a cast time maybe, to limit it) would make their resource management a bit more interesting than just "waiting for bullets aka, runes aka, energy." There are enough classes that have to sit around and wait for a resource to magically generate itself.
I see no harm in letting hunters use dual-pistols too, even if it is a bit silly. Even other "weird" weapon types like intellect axes or strength polearms can be used by more than one class, so the more hunters and MH's can share weapons, the better.
I agree Worgen wouldn't be a perfect fit for the class, but they DO have a few things going for them, just like Draenei. Gilneans in recent years have
had to learn to hunt monsters like the invading Forsaken, their undead constructs, and the mindless Worgen affected by the curse. They would be the perfect race to deliver a Glove Slap (this is the most important reason!!), and as NPCs, many of them seem to like to use firearms as a weapon. With their history of druidism/harvest-witchery, they seem more in-tune to the wilds and what it has to offer, and they're more likely than Draenei to "do whatever it takes", including some questionable practices. And hey...undead abominations and a werewolf plague knocked down their wall and disturbed their nice quiet lives, I could see them wanting to mercilessly hunt down them and their ilk.
The only thing is...I'm just not sure I see Draenei being a great fit either. Many of them are adept with technology and are also very spiritual/magical, and love crusading against Bad Things, so that's great...But I don't think all those interests would very often come together to create utilities as ethically-questionable as injectors (which to me implies exploitation of their victims, something I think they would kind of be against). As a race, they seem to prefer defending themselves with magic/crystal melee weapons, rather than guns. And they're just a bit too worried about the legion to be crusading against random beasts and monsters. :P
Great idea though, I like it. I love reading well thought out class concepts.
I think "junk" needs to be called something else - "scrap" maybe. "Junk" is just WAY too ripe for exploitation. :|