My realtor recommended a guy to me, but he injured his shoulder and can't get through a hatch to see the roof.

Workers comp covers injured employees, subs, etcAll 3 are very different and applicable in their own ways

Regarding the roomate situation, my agent told me the insurance will likely cover the property damage caused by the roomate,but if he got injured due to my liability, that won’t be insured. 

Sorry to hear you were injured.  

Firing a gun through a window could have injured or killed someone, and leaving him in place is a huge liability.

He didn't want to budge from the 15k and I upped my offer to 13k.Seller claims that the borrower is solid and was behind after being injured and missing work.

Difficult choices.If you take matters into your own hands and decide to run her down in the street make sure she is dead and not just injured.

If I were you I'd politely extend my deepest sympathy for her car, express relief that no one was injured, thank her for bringing the tree to my attention for the first time, and wish her the best of luck with a potential insurance claim with her car insurance.

Liability is a trickier subject but if someone was injured it'd go right back on you.

Not only is there a high risk of water damage there is also the risk of a improperly installed unit falling and injuring/killing someone.