If I have a unit of Fakyeli embarked in an Airborne Transport and the platoon has the "Air Cavarly" special rule, and I do a March Move with the Helicopter, then disembark the Fakyeli and then move again - does this count as a March Move for the Fakyeli squad? Since they have the Assault rule, this means their March Move cannot be reacted to - which is what I would like.

Mostly sure disembark is its own special action that is not a move and cannot be reacted to, so probably not, I don't have my book with me right now but the transport rules in the core book would be the place to look.

Disembarking from any vehicle is an action that is not a move action and does not provoke a reaction. Since an embarked Fakyeli unit needs to spend one action to disembark, they cannot make a march move - a march move requires both actions. After disembarking, the Fakyeli unit can either make a move action or an attack action. So, they cannot take advantage of assault (which requires a march move) on the turn they disembark.