Also, as our real-estate "empire" has grown, we've made some adjustments. 

It's an adjustable loan so the goal is to get a fixed loan.

No, there isn't BUT yes, changes are happening, a person must pivot and adjust in rapid manner, again that is my "jamb", I am called a deal engineer for a reason. 

As soon as you bring leverage into the discussion you’re changing the risk adjusted return.

Sounds like I have more to adjust and evaluate, this probably isn't the property for us but it was good education trying to evaluate.

Your tax will be determined by the difference between your adjusted cost basis (original cost plus improvements - depreciation)  and your net sales price. 

A different rate for investors vs residents is new to me.To some extent it's a suckers game to nab the uninitiated, in that the assessed value is never the market value, and you have to know the adjustment factor to calculate the actual assessment.

@Erjia Mao it does give you the option to pay the lowest possible payment but Helocs are usually a variable interest rate tied to the prime rate which adjusts every quarter I believe so your rate may slightly adjust once a quarter.

This is a good point and I'll need to adjust my returns if I were to sell it for 180k now.

Though rates will adjust on that type of loan.