It's ultimately up to you.

However the damage is paid for, the individual who leased from you is: 1) ultimately responsible, even for their guests and damage caused by them.2) allowed a "guest" unaccompanied?

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Ultimately, I would like to buy properties with them and pay the entire costs including renovations.The plan would be to do BRRRR with this partner.

I would start with "The Ultimate Beginner's Guide to Home Loans", "The Ultimate Beginner's Guide to Real Estate Investing", and "How to Buy a Duplex: The Ultimate Step by Step Guide".

The threshold in which the math works for me and my strategy is fairly wide, but ultimately I'm trying to decide how much to put down....A) 15% (aprox 60k- have close to zero cash flow but have 20k more in the bank )v.s.B) 20% (aprox 80k - $200 of monthly cashflow but have 20k less in the bank)I love the idea of having more cash on-hand for any big expenses that come up and/or also as a nice chunk to get started on my next investment.

And most of us are playing the long game here...time is the ultimate multiplier and hedge.https://irma.nps.gov/STATS/

Ultimately I would like to utilize this home to get my foot in the door to real estate investing.

@Daniel Young if it's ultimately a flip and you're confident that it'll sell once listed, I'd just pull a credit card cash advance. 

They will undoubtedly be problematic down the road if they do ultimately take it.