Deer manure, that's an interesting one! Hmmm. You can look up manure values on google for cow, chicken, pig, etc. They are probably eating and taking up more than putting down but interesting, hard to say. Soil test is really the answer.
Urea in bags is untreated. Unless you find some specialty stuff or lawn fertilizer (which as far as I know almost always has 2,4-d added, etc, which you don't want). Usually you get bulk treated at coop- they apply it. There's 2 methods.... Agritain or Nitrain is a liquid that's treated to Urea to stabilize it or Smart Nitrogen (I think that's what it's called or ESN) which is coated with polymer I think. I believe ESN would be slower to release but there's plenty of info out there to confirm & should be fine. Both work fine and I've used both.