These days with Subject To, I just have them text me a picture of the kitchen, bathroom and roof so I can figure out if I'm interested enough to talk further.

Property came with new roof, new AC units and was overall in good condition.

We removed a large tree that towered over the roof causing a mess with falling debris on the roof and blocked all sun which left too much moisture.

I would think the exposure would be the building were to partially blow over or the roof blew up and dumped large amounts of water in the building. 

This could be a small roof leak or maybe water that got in during a windy storm. 

That answer is hugely dependent on the size of the home, the number of rooms, age of things like the roof and such.

Pick your dilemma - tenant quits paying rent and squats in the house for 2 months while you spend $1,000 to evict them, the AC goes out and it's $5,000 to repair, you need a new water heater, or roof, etc.  

House was built in 1995 so I am thinking that I will need a roof for it soon and central heating/cooling is six years old.

Roof was sagging a little and needed some work.

20 years is the typical life span for roofs and mechanicals, so if the house is 20 years old, you may need to replace those, which could add $7-10K to your rehab costs.