Fresh out of college, we moved to Dallas, TX to take on entry level jobs making very minimal amounts of money.

If so you can look into Cash Re-Fi (not as popular these days with high rates) OR look into Home Equity Loan / Home Equity Line of Credit.

MF houses provide improved cash flow, economies of scale, and faster portfolio development, but they may not appreciate as quickly.

He is overbidding by an insane amount and still losing properties, usually to cash offers.I haven't done research into this for personal real estate purchases so looking for some pros/cons here from my idea.Can you take out a hard money loan to make a cash offer on a personal home.

LTR will probably be the least profitable, but also the most stable and least amount of work. 

I disagree with some others here - I LOVE mobile home deals and will often send out mailers JUST to target mobile home lots.You need to know the year of the mobile so you can assign a flat dollar amount value to it, then comp the land.

Essentially, I want all cash flow/expenses to be flowing in and out of a business account rather than my personal bank accounts. 

The way I see it, a brand spanking new duplex wouldn't be the smartest deal because of the high purchase price and you'd likely not cash flow, if not be in the negative.

Don't borrow or cash out from the retirement account. 

You can put less money down and still get some money coming in (not cashing flowing positive).