First of all: Magic disrupting technology gets canned.
The different races can all be done via aspects. Trolls get access to Recovery.
Gun Mages are mostly Evocation users with Magelock pistols as their foci. A fintlock should be Weapon:3. As for Warcasters, most of them use Evocation, and controlling Warjacks is either worth
- if the warjack is just an NPC fighting alongside the party or [-2] if it's more in line with a Summoning/Binding ritual. Same for Warlocks. Warcaster armor is just an enchanted item with Block/Armor. Warlocks transferring damage is not part of the Fate mechanics, and I suggest leaving that one out.
Now, as for the average warjack in a DF setting:
Hulking Size [-2]
Inhuman Strength [-2] and Inhuman Toughness [-2] for light warjacks
Supernatural versions for heavy warjacks
Claws [-1] for various warjack weapons
Aquatic [-1] for certain Cryx/Merc warjacks
MAT 6 is ~Rating 3 skill, which makes them the equivalent of a high quality necromantic minion.