1) Who's paying real estate taxes?

I use the rental calculator all the time to analyze deals as well as some of the other features and then write off the costs as education at tax time.

That's how the tax man see it.

It’s a pretty poor business practice to change the lease after the tenants signed. 2) I would find it easy to believe that somewhere in your contract it would say you owe the year’s management fees or there’s a 30-90 day termination period or any other thing that could cost you at least another month’s 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).

Property Tax GIS system. 

If you owe the full 700k, you may need to bring money to closing to pay down that balance.You would also need to financially qualify to cover that new monthly payment.   

In theory my only costs would be purchase of the lot + associated fees, taxes, and engineering services (which I could do a portion of on my own time). 

Mortgage payments, real estate taxes, utilities, property management fees, landlord insurance, and upkeep and repairs are examples of fixed expenses.

Expenses: Insurance is about $145/m property tax about $208/m (my guess, lowkey the property got tax assessed at $89k in 2022 and now its worth what it is now so I'm guessing $2450 a year).