Stick around for 'others' to reply. (I can't imagine my Follow-up being the only one, agreeing or disagreeing.) Anyways, ...
Consider stopping by your local Stone & Quarry Pit. There are PLENTY of Masons going in and out of there. You can also visit a Concrete Dispatcher. You know, where the concrete trucks get their concrete? SOMEONE has to know SOMEONE. Sometimes, when you're walking around downtown or something, take a close look at what you're walking on. If it looks 'stamped', talk to the Builders or Maintenance folks, or whoever can help you, in order to find out who did the work.
Regarding the cracks, if they haven't moved for years, I'm sure they aren't going anyways. It's possible that the added weight of the NEW concrete (assuming you go the stamped route) may cause the old stuff to 'move', talk to your contractor about that AND about reinforcing the new pour. From there, he'll tell you what needs to be done.
Stick around, still, to see what others have to say. My best to ya and hope this helps.