I would not take that owner financing if possible, I don't know about your market but that interest rate is double a good cap rate in CA and more than most hard money lenders would charge. 

I was looking at gas and water paid by landlord and thought I could charge $55 each for gas and water as flat every month fee.

In addition, the PM charges their "new tenant fee" equivalent to one month of rent ($1000). 

So if you put $100k in a savings account with them, they might be able to use that $100k as the basis to lend out $500k... and charge interest on it.

Hi Kevin, I am not sure, but I will bet @Denise Evans has a good opinion on it.

Your best bet is to find a multi-family property that is mis-managed, has below-market rents, or needs to be renovated; then you can take the steps necessary to improve its performance.

I can possibly help some and I won’t charge you anything

I am planing to put management company to manage my house, but it feels like they can charge any amount of money and i am in their hands.

What’s a fair ballpark figure for a real estate attorney to charge for supervising my process of finding a tenant; over looking the section 8 contract and my own lease contract/documentations with the tenant; I’ll be using the online tools for application, credit report / background check and customized lease contract.

Management companies are almost all alike in the way they run and the fees they charge.