As for those drawings, the green one seems closest to what I imagine we'll get, and the purple one is good for a leader of some sort. The red snakeman's neck looks a little too difficult to make, but that's just me.
I predict lots of blade-y stuff. Fang-like protrusions on vehicles and a snake's face, similar to the skulls on the skeletons' vehicles.
Only the Rattle Copter seems like a definite vehicle for the snakemen, and I'm probably overthinking this, but I'm imagining a green helicopter in the style of a giant snake head, maybe with a mouth. I'll see if I can do a quick drawing to demonstrate my idea.