Is it about price or availability? Range guns get the most use.... My I suggest looking on gunbroker.com? I have had excellent luck finding guns there for a great price.
I would not. Range guns are typically used by novices and or by people testing a gun out and get abused. I personally never buy a used gun. I like to break my guns in myself.
Depends if they would let me break it down, depends on the discounted price they were going to give me, depends on whether I could shoot it first, and it would depend on the model.
It's really difficult to be hard on a revolver to the point that it would need major work. If the hammer pull feels good, the cylinder turns freely, and the trigger pull feels great and you are getting a good discount on it being a really used gun, then I would say go for it.
Personally, the 686 + is a great gun. It gives you the option of .357, .38, and .38+. And you get 7 shots instead of the normal 6. I've only heard one problem and that was an ammo thing, not a gun thing. Magtech .357's expanded and the casings were difficult to remove and left much powder residue. I haven't experienced that, I have only read that.
At worst, you replace a few springs and the firing pin, at best you don't.
I would ask them how much they would be willing to pay you for a used gun of that model before discussing buying one. Then use that as leverage. I agree, a revolver has fewer moving parts, and is less likely to be in the "abused" category. The comment about the range having an armorer/gunsmith that maintains their rentals is also a good point.