The fact that you're riding on cracked roads makes me think that you'll want to go with steel. Sure it'll be a bit heavier, but when you hop to a light bike it'll be like you're flying, and steel doesn't have the fatigue properties that carbon has (epoxy you know, not at all ductile). It'll also probably be a more affordable bike, that can never hurt, especially if the biking is starting to take a toll on the old credit cards. Steel will, as stated above, endure an impact much better than a composite material. WW bikes have their place, but for the kind of roads you'll be on I'd go with something a bit more robust.
Also, you might want to spring for a set of wheels, if for no other reason than to have a backup pair in case you nail a pothole (not hard to do).