All the off market sellers that we worked with wanted 50% or more of a down payment with seller financing.

But those didn’t cash flow as good so I threw more $ down or my lender gave me a much better interest rate with a bigger down payment.

But the garage is not included since I need it for storage of my tools and supplies. 

Easiest and least costly is to go there and spend a week or so to get everything in order.Another one is to hire someone trustworthy and pay them to put it in their garage or in a storage unit for a month

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

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

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

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. 

Your minimum down payment amount for a 2-4 unit will be about the same as an often required 20-25% down payment on a co-op.