I should look at the expenses vs the income (rent collected) and not the selling price of the property. 

The contract was a simple 3 page one and I wrote this in.Also, it is a single family being rented as a rooming house (which is technically not legal here).

I was chatting with some of my lending buddies at big banks and they are all backing away from the CRE space including office because operating costs are increasing more quickly than rents.

We plan to stay in the new primary residence for a long time because we love the location, the neighborhood, and the land.

That's a little harder to answer.How many of those government, (none military) jobs (including contractors) rent in the D.C.

If you walked into a bank, your pre-approval would likely never qualify for a house hack duplex.Did they count 75% of the expected rent towards your DTI? 

For example, I mention that every adult must pay a $XX application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

All rents you get from this property has to go back into the SDIRA but if you get a 20 year mortgage (that the rent can cover) and can pay the rental off by age 65 you will have turned that $90K into several hundred thousand’s of paid off real estate.

We source from suppliers that get them directly from the ships - these are normally near port cities (ours is located in Houston, TX).

There's no reason to provide details, though I do let people know if anyone asks that we do not accept bulk up-front rent payments or anything like that because I absolutely do not want a prospective tenant to think that someone else swooped in with a bunch of cash last minute.