The full payment would be around $5,400 : The ADU could rent for $2k per month and you would be left with $3,400 per month on the main home.

.- get into real estate with a lower rate and lesser percentage down payment.

If not I don't like this as the payment will sky rocket after the 0% intro period.2.

If it costs you $20k to do a refi right now is that worth it on the payment difference?

The fact that our current rate is only 3% doesn't help the refi situation, as we probably would not be able to afford (or would at least struggle to afford) the payment on the new mortgage with the higher rate and principal.I think the best way to max cash flow would be with a small multifamily that needs moderate rehab.

Start with your primary, rent out any spare bedrooms "house hack"Use that to practice upgrades, kitchen, bathroom, curb appeal... etcNow you have experience as a landlord and flipper, use that to buy a distressed propertyAdd 40% equity to the property through home makeover, refinance into a low cost mortgageNow you are cashflowing a healthy margin on a second property, use that to build equity over time, cashout later and buy your duplex/quad.If it's going to take you 10 years to save up a down payment for a small apartment building, yeah it makes more sense to start growing your portfolio with cheap SFR flips instead.Every market is different, every borrower is different, every property is different, it would be ill-advised to recommend anything without recognizing the individual's nuanced goals and objectives with their next acquisition.

We chose these properties for cash flow opportunity and because they work nicely for house hacking because the unit you are occupying is a percentage of a smaller mortgage payment.  

You can do FHA with 3.5% down- less in some states with down payment assistance, but you're better off doing a conventional at 5% down if you can swing it. 

FHA-Owner Occupancy Loan, to limit down payment to be able to utilize for maintenance

The minimum down payment for a property in this price range would be roughly $27K.That said, you also need to account for bank closing costs, inspection costs, appraisal, attorney fee, and title costs.Your scenario may require a seller's concession to account for these additional expenses.Investing with $50K is totally possible in this market but your journey may be met by challenges i.e.