The recently renovated unit will need a refrigerator and stove. 

And just recently had to do some major renovations to the downstairs unit after my first tenant trashed the place, stole my washer, and dryer, and ruined the refrigerator.

If the refrigerator stops working, that's maybe 5% of the value of the home (on the high end) or $3.30 per day.

So it might take a while to get that done.2. 1 small dent on the door of the refrigerator - how much does this damage worth?

Day after tenant moved in, we installed a brand new stainless refrigerator.

People that can only afford $575 are very unlikely to have their own refrigerator or dishwasher. 

In a college town north of me, you may not have more than 3 unrelated people living in a unit.Consider getting an extra refrigerator.

Installed a new dishwasher along with a stainless refrigerator and stove.

She wants refrigerator air filter changed and my husband went to the house and smell nothing, even he switch on the AC.

(Don't forget that you need plinths for spacing if you have cabinets meet at the corners so that all your drawers open and your refrigerator can't be right next to the wall to get full door swing; we also use stock ikea cubbies and ikea 15" shallow depth base cabinets when we don't have room for full 25" countertops).