Well the last time they were selling it, no one would buy that house even though it was priced $100k below what it would typically sell for.  

Typically, credit cards have interest rates in the high teens or higher.  

How much is the typical home insurance with standard liabilities cost for multi-family units around Boston areas? 

The LLC would then deduct the mortgage interest, and the loan would only be recourse to your dad (reported on his K-1).

I typically am aim at the multi units.

Typically owner financing is a tool sellers use to move a property along.  

Hopefully that never happens to you and it doesn't happen to a lot of good investors, but you need to know that there are no counter-options for you to take if you're not registered in that state, typically through an LLC. 

How long does is a typical day for RE agents?

Brokers typically have errors and emissions (E & 0 insurance) specifically for misrepresentation of facts or forgetting a disclosure.

I feel that it's probably more involved than using a typical property inspector who generally deal with SFR.