You can also check online resources like BiggerPockets or Roofstock, which offer general CapEx guidelines based on property type and age.These methods should help you perform a solid preliminary analysis.

You can also use the Enemy Method to check the rates of your competitors.

Down payment: Can you give us some of your reasons for wanting the larger down?

There is no 'per square foot' method that is accurate....At least until you have quite done a few.... 

He could try to evict you for non-payment of rent.

My guess is they missed a payment, then started up again. 

No, just inform them you are the new owner (they may want proof) and provide them with the address to send payments. 

Your contract is evidenced by the spreadsheet, payments, and likely other communication about the work.

Then you will have a principal and interest payment of around $13,450.00 plus Taxes and insurance so add in another $2800 for $16,250.00 a month. 

Someone will reach out to you. split direct mail cost with the best, pursue other marketing methods with the person.