Is it Cash Flow, Cap Rate, COC, all three or something else?  

Most of these properties are going to take me 6-7 years to actually have positive cash flow.

We have been able to set aside some cash/savings over the past few years of marriage and are ready to invest in real estate.

Maybe they could provide you with info on where to buy the machines.  ”Payrange” also offers users incentives to earn points towards the purchase time of a machine.  

You can offer them cash for keys-give them money to move.

Initially, I want to buy a little condo and rent it out, to start cash flowing.

Buy something in class B neighborhood or emerging class C neighborhood with higher cash upfront low leverage to ensure you have enough cashflow in worst case scenario and see how it performs.

Maybe the best bet is a rental refi on one of the two existing properties to be able to get a new home all cash?

I would and have cashed out my 401k (not Solo) to invest in Self Storage.

Timeline should be Three months: Save cash.