Also don't forget that hard inquires also reduce your score. 

Need to maximize deductions and depreciation over the remaining months of 2018 to significantly reduce taxes.

I'm off this property for now, but will stay in touch with the seller in case he wishes to substantially reduce the price at some point and bail out.  

I want to buy a house for myself in the next year, I’m worried that taking on the debt of these apartments will reduce my buying power.

By standardizing and buying in bulk, they are able to reduce material costs.

If you can get seller to reduce price due to not vacating a unit, sure that would be great.

I'm hoping he might reduce the cost in exchange for a longer term.

House hacking is definitely the best strategy for anyone looking to significantly reduce their living expenses.

I'm considering developing properties and using pre fab home kits to reduce build time and keep the money moving. 

In the latter scenario, you don't cash out the investment property to repay the primary cash out; rather, you cash out the investment property to buy another investment property.One more thing to keep in mind - when a heloc and the market turns, the bank can reduce the balance of the line, reducing your purchasing power.