hoss,
Tractors have an hour meter. Similar to a car's speedometer, they "lie". However, on a big tractor, ~3500 hours would be considered not bad. ~6500 would be a lot. Course that is very subjective. On a compact, I would stay below 1000 hours depending on shape and who has it. Private, look around and see what it was used for. At a dealer, it could be anyone's guess.
There are anomalies within makes. For instance, a Ford 5000 with a manual shift can still bring a good buck. A Ford 5000 with the "Selectomatic" (auto) is dog.
Do you have any understanding of terms like 3pt, outlets, shuttle shift, etc. ? Ask away.
What kind of cutting are you talking, grass or brush or both? And how much? For the road maintenance, you can pick up a 3pt rear blade. That will work for snow up to a foot or so and for the grading. I would want one at least 7 feet wide. Get one with adjustable shoes to keep the blade up on soft surfaces. If you can go with hydraulic angle, it will save many trips off the seat and let you do a nicer job. You may also want to add a landscape or "york" rake too.