I've had many clients utilize the rent by room strategy to great success. 

Hi Rafael,You can start with a SFR or duplex if you'd like to avoid using a property manager, but if you really want to scale up you should be utilizing a property manager.

Or just used $15k as a downpayment and then had to make a couple months of payments to make the property ready, pay for inspections and repairs, commissions, utilities, advertising, and then it sat empty for a month and you had to make another payment?

I also utilize subordination of the mortgage and substitution of collateral where appropriate to create the “enhanced” returns that I seek.  

However, looking at some payment processing options like stripe it seems there is close to a 3 percent fee for utilizing the service.

An investor-friendly lender will help you devise a plan for savings and debt paydown.I'd also begin looking into which areas you'd like to invest in as well as strategies to utilize (i.e. househacking). 

The basics are I would rent a number of units from the syndication LLC, would be responsible for management and expenses (ie utilities), and then I would keep a portion of the profit (basically my upside for managing the mid term rental units) and the other portion of the profit would go to the syndication LLC which now gets over market rent.

Vacant lots can go for as little as $5000 - $7500 and are usually between other houses so you at least know utilities should be on or near your site. 

You will get exceptions on your income at small local credit unions and banks who will utilize your 1099 income over W2 income more loosly, nonetheless it all starts with you completing your taxes.

If you are looking to just add an opening between the units since you are utilizing it as one dwelling, then typically you could just add a fire rated door.