It tells you how much interest you paid on your mortgages.

I understand that as the buyer, the benefit is taking over the seller's mortgage payments which may be more favorable thank taking on a PITI in the current market.What I don't understand is, what is the benefit to the seller?

You don't need an LLC for one mortgaged property.  

I would look up Deeds in your county recording dept online and search through the pages until you see one that has an entity TIC.  

(online payment, venmo, cash/check, etc).Please provide proof of utilities paid on time and in good standing for water/sewer and trash/recycling.Are there any unresolved tenant disputes, outstanding repair requests, or complaints from any existing tenants?

Also, will she be able to qualify for a mortgage, if not, putting all of her money towards a house is not anything I would do.What sort of pension will she have?

Do people regularly invest in properties they can’t afford the mortgage of with full vacancy?

Is your DSCR ratio greater than 1-meaning are you cash flowing (according to the lender's criteria of mortgage, property taxes and insurance (and HOA) if applicable).

But I've been accepting Venmo & other forms of online payments that go into personal accounts for 10 years now from dozens of tenants. 

It's obviously better than owning without any offset to that mortgage payment.