I think an agent should be able to give you an idea of the age of the roof or funace but nothing more than that unless they know for sure. The agent's info may come from statements (either written or oral) from the seller but it is your home inspection that will will reveal more accurate info. I am required to have my sellers fill out a property disclosure and unless the air conditioner, water heater, roof and the like were replaced fairly recently and they have readily accessible paid receipts I prefer their answer to be "don't know." In any event, you should not rely on the accuracy of statements by the seller or the agent - - instead you should have the home inspected by a licensed inspector.
As for untility costs, if a buyer wants to know what the current owner's average costs are I will attempt to obtain that information. However, I always explain that in addition to annual variations in mean temperatures we humans have our own personal thermostat. Some like it cooler and some like it warmer.... more