Zillow is clueless with duplex.The upper cap is SFH but how lower should a duplex be when comparing with a comparable specs SFH?

If you measure the totality of your investment, mean cash flow, debt reduction, appreciation, rent growth etc you will always make more money in the areas of high demand like DC, Boston, Seattle etc than you will make in a pure cash flow market like you will in the mid west.There is always the possibility of your rate going higher, but thats the trade off of a lower rate with the arm.

Because they will lose out on tax revenue, since you got the house for lower than it it is currently assessed at you can fight your taxes and get them lowered.

If you been filing US tax returns while in Japan (legally you should have) then even with a lower credit score you could possibly get a loan. 

How would I distribute profits or will it be considered pass through income at new lower rate?

Unless your goal is to pay off the mortgage, then it's better off with lower tax.

To over simplify, historically  any coastal states will have a greater appreciation in value then in land states, however middle states have a greater possibility of cash flow, in part due to their lower entry price. 

@Cindy ChanIf your mother gifts it to you - your basis in the property is the lower of her basis or fair market value at time of transfer.Ex. she brought it for $100,000 10 years agoit is now worth $90,000Your basis if she transferred the property to you would be $90,000 + the cost of any repairs you made.If the basis did go down - I would prolly see if she can sell you the property.

They set up a phone call and I am sure they are going to lower the price.

Hmmm, options are a legitimate way to make a lot of money in a SDIRA, but it sounds like it might be a fight if the IRS decides to make a case because of all the abuses.