The next step is to pull out some cash typically a cash out refinance and use that cash to put down on another investment property.Are you strictly using your liquid reserves/earned income to buy versus using the equity to pull cash out?

I will have about 50k liquid after selling my current flip without selling my primary. 

If you liquidate your dad's home, the Big Enemy to pulling out all of his ~$100K in equity will be frictional costs (agent's commission, buyer negotiation, holding costs, etc.).

You'll always be liquid, less capex exposure, and you have more of your time. but if your ego insists you keep 7, then make more money and spend more time with this. 

The fed has been and will continue to liquidate their massive balance sheet (from over-stimulus) and keep rates high until stuff starts to break.

I would always specify that is primarily not "solely" based on the property - Credit and liquid reserves are still a significant part of the underwrite

I have 100k liquid to put down. 

As for the down payment, I would make sure you always have some cash on the side lines for liquidity as lenders will want to see cash amounts outside of credit lines.

I have about 15k liquid cash and live in MA.

The default mode of operation for mini-splits is to run the fan continuously 24/7, which causes high humidity because all of the condensation is being blown back into the building.You can get top tier mitsubishi units for cheap at surplus city liquidators.