Older home, Good deal?

[Qwee Parker]

Hey, coming to you all for a bit of advice: After 4 months of searching for a duplex, I finally got an offer accepted! It is a 2 bedroom upper and 3 bedroom lower unit.... Beautiful home and this is super exciting, but I also have some concerns that I'm not sure I should let fly or am over-analyzing. 1. it is a older home (1924). With that said, it does have more wear and tear. After my inspection, I learned that there is significant damage with the roof, the chimney is in disrepair, the furnace and water heater are just at their life expectancy, and their were rodent droppings found in the upper unit furnace (inspector is guessing it is from the attic). Also, There has been signs of moisture through the home (water staining on the basement floor and upper unit ceiling). These are the major issues to note, though there are other minor ones that I'm not as hung up on. The seller has agreed to pay for a new roof and put the home under warranty for 1 year. He will not include fixing the chimney. My fear is that after 1 year and a day, the furnace and/or water heater go out....and I'm left with a huge bill to replace those. Should I remain stuck to my guns on him replacing the furnace and water heater? Should I care about the rodent droppings as much as I do? Is the warranty something I should find comforting in this situation? I am trying to keep in mind it is an older home, but I also do not know how much I should give or take for this older home. Any advice or thoughts would be greatly appreciated!