Good points covered here already but I think I can add a few thoughts to the discussion.
The questions you are asked is going to do a lot with how savvy the buyer is.
Have the stove clean and running when you show the house if possible. If the intent to to help show value that should help. When questions come up keep the answers to the basics. I think Rona made an excellent point on this but I think you could expand a bit on some details such as pellet storage, tons burned per year, cost savings experienced and the annual professional maintenance cost. These are questions only the seller can answer. Let the potential buyer do their own due diligence on the model and upkeep of owning a pellet stove. Mention Hearth.com as an excellent resource on the subject
.
You may also want to ask the seller if they can produce the permit (if required) and the dealer that can service the stove so the information can be transferred to the new owner.
Last but not least, some folks may have concerns about their kids getting burned. Some stoves have hotter surfaces than others so back to buyer DYODD. However they do sell gates to keep the little ones at bay.