I was cashflow positive while living in the property and knew I would cash flow even more at my move out.

My focus is on buy and hold, cash flow properties. 

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.

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.

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.

In my area the water company will forgive excess usage if it can verify there was a temporary water leak causing it. 

Do not focus on cash flow first in Philly or you will end up in a C-/D+.You HAVE to work with an agent who has been in Philly for a long time to have success and who owns properties there.