These loans are short-term as you mentioned, typically 12 months, so you'll need to refinance before that balloon comes due.

typically with seller finance there would be some period of monthly payments and then a balloon where you pay off the balance in full. 

The IRS generally does not allow you to deduct expenses for a property that has not been placed into service, as deductions typically apply to operational properties actively being used to produce income.

Typically, we see anywhere from $600 to over $1000 per unit (maintenance and turn costs)  depending on these factors. 

Perhaps do a case study with a hypothetical deal you think is typical for what you are looking at and compare it to the alternative investments you might use and their expected returns.

No reason to spend $1000-$1200 on a typical 1031 QIMathew 

The way to get access is typically reaching out to the sponsor and getting the PPM and the documents you need to do a thorough review.

For bigger jobs I have went with the "Have it delivered and I will cut the money to the driver".

Helps with your debt to income, better opportunities at cash flow, and typically requires less down to purchase.In regards to challenges, I usually build in an extra 10-15% to deal with things that I can't see behind the walls, including dry rot, electrical or plumbing issues, etc.

In investing that's typically done by exchanging one asset for another rather than using cash as an intermediary (which would require you to time the market perfectly).