Southeastern PA is much too broad.

@Ran Iarovichtoo broad a question.one way to think about rentals (everything from a single family to a 100 unit) is that each one is its own little business.all of my rentals are different. 

On the comfort spectrum of house hacking, my fiancee and I prefer separate units, but I could always consider doing a live-in flip for a second property if I don't find a house hack! 

Baltimore's culture is quirky and it's called Charm City because it has a certain charm, but does not broadly appeal to everyone.

You just have to be ok with active income there and passive somewhere else (broadly speaking).

I know this is a broad question but me and my brother have agreed to use this money purely for investing and to help us in our goal with financial freedom and to set our mother up for success.

A better apples to apples comparison would be REITs or broad index funds, which performs better in general? 

I can say there's a very broad range of strategies that can work for you here.

While it's there, he invests it a balanced portfolio of 60-70% broad based index funds and the remainder in domestic bonds.Then, with the other half, put 25% into syndication deals, 25% into dividend producing stocks, and 50% he dabbles with in things like HML, house flipping, etc.

This is a brief and broad overview of how the development process works what's required before you get too far down the road or purchase a property.