Also, the banks that did approve me told me that they could only use the rental income from the other units (75% of it) for an FHA loan, not a conventional with 5% down (which was my goal to avoid upfront PMI and have it automatically drop off at 78% LTV).

If I buy a house for $400k, and the market drops and the house is now worth $300k, I am under water.

Total interest paid drops to $41,857.25 which is a savings of $35,808.08 (46.10%).We could improve upon this a little more by making bi-weekly payments of $291.88 + 140.38 = $432.26.  

If rates drop in the future, refinancing again could lower your payment, but it’s good to make sure the numbers work now just in case.

We just discovered a crack in the concrete slab foundation that is a borderline major problem:- It is a vertical crack about 1/8 inch wide that is at least 9ft long, which is causing a 3/4 inch drop in the flooring and some evidence of old (luckily) limited moisture and termite intrusion. - BUT, it also appears old and probably a symptom of the original house settling.

Then it dropped to like 30% of its original value.

If fed ex driver dropped it off near front door, no one would be stealing the package.  

@Itay Heled Last year, Furnished Finder published a document called "the state of mid term rentals" and it showed that the users of FF want studios, 1 bed and 2 bed proerties. the demand for 3-4 bedrooms significantly drop. 

If anything, we're now seeing data that suggests there isnt much reason for rates to drop significantly any time soon.

Meaning any of your Helocs can be closed or reduced at any point if any of your banks feel you are over leveraged, miss a payment, credit score drops, even by mistake it happens all the time.I would get rid of the Helocs and put some cash in your bank so you can use that versus a Heloc.