I paid this mortgage off years ago.22. 

Off street parking, quiet dead end street.

I was wiped out as second lien holder which got me to thinking about legitimetly becoming a private lender.My question is if I already make 7.5% off a few of my 250k condos, then how does private lenders (not hard money lenders) make money off charging 7-8% returns when they can just purchase condos in cash for the same CAP rate?

Sounds like you are off to a reat start.

So when you sell the asset, that payoff is in the loan file and title company knows to pay that off and pay you the gravy. 

We are now in a position where we have 4 investment properties completely paid off making us money and I have a high paying W2 job that allows us to feel comfortable enough for him to quit his W2 job and start investing in real estate full time.So my question is… where can we go to get advice on how to move forward with this in regard to the best way to structure our growing real estate rental business?

Perhaps could argue you had to relocate for work and write off some moving expenses... 

More on DSCR loans: DSCR loans are based off of down payment, credit score and either actual or market rents so it helps to supercharge an investor's real estate goals and net worth.

If you set it up with a car rental service like Turo are likely protecting yourself/car more from potential issues and damage and may be able to keep it off platform and only make it available to your renters (not sure on that last part but just a thought).Also, from a lender perspective it could complicate things if you are looking to refinance one day and have car payments included in the lease payments/on the lease.

We have unit vacancy that fluctuates, but safe to say 4 units per month is a good baseline that our new (In-house Leasing) agent would get off the bat.