Since an executor/personal representative has not been appointed by the court and no Trust is in place, there is no one who can sign for the deceased. 

You should look into DSCR Loans - many investors like yourself typically move to this loan product once they max out with DTI/qualifying conventionally - a bit higher in rate than conventional mortgages - but no DTI ratio or tax returns/income verification makes a much easier qualification process and LLCs are 100% ok (even as sole owner) and actually often preferred.PS - published a 10-part article series here on BP last year on everything you'd want to know on these loan types - sharing links below, hope it can help!

You’ll want to have your numbers in order—this means understanding how much the property could sell for, what repairs might be needed, and what kind of offer makes sense for you.When you do contact the homeowner, be upfront and personable.

I personally do not care for black cabinets and black gleam flooring.

There is likely a phone number and persons name that will come up, that you can reference, since he is having bills that arrive to the mailbox and packages to the door with his name on them.You could make it a pre-condition to the seller that he allow a background check on the tenant before closing and your offer is contingent on your approval.Neighbors typically know what's going on in the neighborhood and will know who the guy is and if he is a trouble maker.He probably has a car and a private detective can run the plates.And so on.The information is readily available is the knowledge is worth knowing.

With a few inquiries from auto dealers. they shared 3 months bank statement and cash app summary showing 10,000 per month coming and withdrawal as well as withdrawal so maintaining close to 0 balance. 

I own an AirBNB in Denver and I just got a year long request and the person doesn't have any reviews.

I see you mention having an LLC, so I'll share my generic advice on that topic.An LLC is useful for two things: anonymity and legal protection.

Would it be a better idea to invest in a single family home with only my personal capital, or partner with a colleague(s) and go 50/50 or 33/33/33 on a larger multi-unit property?

If you can't keep control of your personal finances, you are highly unlikely to succeed in real estate investing.