If you continue to accumulate rentals, your DIY knowledge will make it easier for you to screen Property Mangement Companies and not get screwed.Refinance ASAP to get rid of PMI/MIP and get a lower rate.Select a 15, 20, 25 or 30 year loan term based on the payment that gives you the "cashflow vs equity buildup" you want.

Also the cashflow won't much unless you have accumulated lot of rental income to cover your full time job income.

Generally small jobs, but they accumulate.

3) If it just sits in the investment account, can I still accumulate taxable interest year after year until I use the cash for an income-generating property or stock?

You can build up from there if all goes according to plan and expand as you accumulate cash flow or pay down your primary residence and travel etc.

I understand you'll build equity in the properties more quickly but if the goal is to accumulate properties, wouldn't it be better to save the cash in order to fund more acquisitions?

It means both safety and huge income and even greater wealth building via appreciation.Wealth accumulation is maximized via max # of doors. 

My business partner and I have been slowly accumulating rental properties in Central Ohio for the past 5 years, we currently own 20 units total, mostly single families with an 8 unit as well. 

Some that are more aggressive at deploying their capital can start with 75 to 80%.FHA is such a picky program it's really easier just to accumulate more cash and bypass all their rules and hit up conventional primary residence for 95% LTV.

We live in the Miami FL area, and we are passionate about accumulating assets that will allow us to reach financial freedom.