While an interesting idea at heart, it's not at all plausibly defined. How could, for example, a species with rudimentary understanding of mathematics and physics operate starships, even if provided with all fuel and spare parts? Even economics wouldn't work, as they have no sense of possession...
Their biology after their uplift is just as unresolved.
I think it should be greatly reworked to live up to the great idea that's hiding behind!
Something I don't quite understand: You say they "hunt and devour members of other races". Then you state that they devour their fallen foes, as a way of purifying them. So do they actively hunt other races, or is it just those that oppose them who are subject to this behaviour?
Otherwise a wonderful sub!