There are a variety of advantages that are associated with being an endotherm or an ectotherm, either of which the Ravager could possess given their mechanics in-game.
But, without more information about Ravagers, it is difficult to even speculate.
Of course the presence of th the Lost Ravager in Winterspring come Cataclysm does give more credence to the idea that they are an endotherm. For both ectotherms and heterotherms would have quite a difficult time surviving in a constantly cold terrestrial environment like Winterspring.
So, with all of that said, I would agree that Ravagers are probably an endotherm.
Now on to the question of if Ravagers have an exoskeleton, or an endoskeleton.

There are quite a few animals with endoskeletons that have armored skin. The dermal plating that crocodiles possess is a good example of this. Jangalian's mention of the Rhino is also a good example.
That being said I believe that if we look at the morphology of the Ravager we can get a better idea.
When I look at the ravager one thing above all of the others catches my eye, its legs.
The legs do not appear to be mammalian in nature, nor do they resemble any vertebrate leg at all. (that I have seen)
Those legs are just too skinny to have an endoskeleton, dermal plating, and all the muscle and connective tissues they would need in those teeny little legs.
However the legs do resemble exoskeletal legs like those of an insect. There would be plenty of room in the legs for any necessary muscle and connective tissue inside of an exoskeletal shell.
This in combination with the fact that the "Chipped Ravager Carapace" is a drop from Ravagers, makes me fairly confident to state that the Ravagers probably have an exoskeleton. (From what we know about the animals in our world of course.)
Of course, Ravagers are a creature from a fantasy game with magic, so who knows?
