Ok, might as well start with what should be the easiest bits.
Power source and Combat role.
We've got 4 classes, and a couple variants. The variants aren't really different enough to warrant changing their sources or roles. So, I'll just focus on the four setting specific classes.
Steamborg
beefy type, usually combat based but I can easily see a stealthy type pop up occasionally(elven most likely).
Based on the setting the Source is pretty easy to state. Steam! Technology would be a good description too but it's not high tech, it's fantasy steampunk.
Thinking it over there are really 2 choices that make sense for the Steamborgs role in combat, Defender or Striker, both of which make good sense. as leader makes little sense for something with a class feature that makes a character lose it's personality(though mechanical/logical orders might process it's a bit of a stretch), and without sinking a lot into it a Steamborg wasn't exactly going to be changing the battlefield horribly with his steam powers. For now I'll call it a hybrid Defender/Striker until I can make a more solid decision (or someone can convince me one way or the other.
Coglayer
Knowledgeable master crafter that maintain fanciful gadgets that do horrible and wondrous things simultaneously. Builders of Mechs, steam gear and the like.
Again Steam is the best for the setting as a power source as it's the complete basis of the Coglayers powers. Without steam the coglayer might as well be throwing rocks by hand... instead of his steam powered auto-Catapult!
The role of the Coglayer is another cause for problems. Good damage dealers, interesting battlefield manipulation abilities, good backup in a mech, interesting and useful support abilities. It's a smattering of everything... that's not terribly helpful... I'll focus on a few abilities.
A lot of the abilities the Coglayer has are easily made into area effects(or are by default) and do decent damage. Most of the other abilities that get used are generally used in non-combat situations and can be left up to time and money for the most part(silly rituals... I know so little about you...) So for the most part we're looking at a controller. It's like a wizards ability to mess around with with combat so I'll give it a wizards role.
Constructors
Specialist wizards that focus on the things the world has to offer now, steamgear, clockwork, and constructs. Control, create, and destroy all are his to do to the metal and stone beasts. They also have the basic abilities and functionalities of a standard wizard...so in short I'll just give Controllers the same role and source as Wizards; Arcane, and controller.
Mech Jockey
Dexterous masters of Mechanized combat, and pretty good out of one too. These guys are the drivers that keep massive machines moving along the ruined landscape of highpoint.
Here I actually have a little doubt on what the source of his abilities are, Martial or Steam. Sure he uses Steam(or manpower, or clockwork, or animated, or undead power sources).... wait a second... it doesn't matter what he drives he's still going to be a badass behind the controls. Martial! it's all in his extensive training, baby!
Just as equally obvious to me is his natural role in combat, he slips in and slips out, cause if he dies... well who's gonna drive the mech? Striker. But he also has potential to direct the flow of combat, in a mech he uses his mind and body to the fullest moving, dodging, attacking, constanly flicking switches, toggling toggles, pressing buttons, and puling levers, he is king of the multi-taskers. Out of the mech I can certainly see a Mech jockey shout warnings and quick orders to finish off what ever the party is fighting quickly to retreat to the relative safety of the Mech. Afterall you can't only be in your mech.... not until you become assimilated at least...
Ok conclusion time!
- Coglayer
Constructor
Mech Jockey
Steamborg