None of the finishes seem very premium (the kitchen is very small). 

Yes, you can purchase notes online, however you’re paying a premium, along with transaction fees and commissions.I would be glad to schedule a call with you to discuss more. 

Premium would be around $250 per year for $1M.The real question is why would you want an Umbrella over the rental property when you have low Liability limits on your auto? 

Many need lots of rehab and sellers are asking a premium.

I looked up the taxes and added them up and came up with a rate of 2.821909%, so that 3% estimate is very close, I got $423.29 so just about $27 less than your $450 per month.The Lawn Care, Repairs, and Capx seem like they are in the right ballpark and same with the Electric, Water and Gas.Now regarding the loan figures -- FHA charges Two Mortgage Insurance fees on each loan; Up Front Mortgage Insurance Premium (UFMIP) and Annual Mortgage Insurance (MIP) paid monthly.At a $180,000 purchase price your Base Loan amount is $173,700 (.965 x $180,000) which you have, but your Total Loan amount, which includes the UFMIP would be $176,739.75.

Generally you're going to pay more or even a premium for seller financing. 

Sounds like it won't sell because they want a premium for a house that needs $40,000 in work.

My basic assumption is that I must consider the premium on a rental property above zillow's estimate price as the "rehab" cost in the Rental Property Calculator.   

Most MFH are sold at such a premium on market that there won't be room for that strategy unless you find something that is vacant and off market.

Even if the home appraises on the day you buy it it will DEVALUE in the first 12 months if it's in a market that has no or little growth.So you have to decide is the peace of mind of a full rehab worth paying a large premium for.