(was a car payment and some accounts under dispute)He answered all of these pretty timely and, because he probably noticed my concern, said he had his parent's lined up to be co-signers if necessary. 

Presumably, they're more serious about their studies and won't be having huge parties that damage your property, they likely receive financial aid and will use those funds to pay your rent, and their parents will probably be a co-signer.  

Fewer people also likely means less ware and tear however you will need to determine what type of parents they are when you do their personal interview.

So I am looking to purchase a house that my parents currently own.

Parent Co-signers? 

I don’t know much about investing, but I’m here to ask for some advice on what my parents should do with their RE investments.

He wants to stay in the house and we, of course as doting parents, do not want to sell to him at the market rate.

Pretty knowledgeable do doing remolding work as have done a lot in my parents and grand parents home and of course what I see while working.

My parents recently looked into purchasing a property in the mountains to use in the winter to go skiing, but rent out when they aren't there (they live in Michigan).

I don’t know much about investing, but I’m here to ask for some advice on what my parents should do with their RE investments.