@Mike Nelson first off i am an agent in Green bay and have good relationships with a lot of the agents in the area so if you have more conversational type questions and want to chat let me know and I will help best I can.
With regard to all of this stuff, I always tell my clients we are looking for "defects" or "safety hazards in the property. Other things like outlet covers and older furnaces etc, that can be seen from the showings and should not be an issue for the buyer. The electrical could be a decent one because it would lead to the buyer not being able to insure the property and of course without insurance, they cant get financing. So that one I can understand them asking for. Same with the fire rated door. Thats safety.
As the seller, your uncle can either offer to fix the things, or maybe there is a number that the buyer would be happy with lowering the price. I would suggest that he ask how the buyer would like to proceed. Often times the buyers are not reasonable and think these fixes are far more expensive than they actually are, so he may be better off just fixing them. Everything is negotiable at all times.
If he needs references for reliable contractors to fix some stuff, let me know and I can point him in the right direction