His parents had a chance to sign a Co sign agreement and declined.

You are allowing a tenant to make a big investment into your property, no matter what you get them to sign to say they're doing it for their own benefit. 

Having your license isn't required to start out and I personally don't feel its worth it until you plan on doing large transaction or more volume. 

There are many signed closing documents.

Individual loans might have more transactions costs but one loan they are all cross collateralized and you may not want that.

He's objecting to the large sign that makes it look the property behind the sign is for sale which it is not.

Cash flow is nice but by itself does not mean that much to me as I make great cash off of transacting commercial real estate deals as a principal broker with my clients.Some investors need large cash flow returns day 1 and others can wait awhile as they make tons of cash from their job or businesses.In those cases they tend to focus more on IRR over time.

In passing, I noticed that another investor had curb stomped my sign and put three more signs of their own in its place...

A commission split aggressive managing broker won't want an agent only for one transaction, do you plan to be honest with your intentions.

AssignmentWith an assignment you sign the purchase contract with your seller and then sign an assignment contract with your buyer.