Petscreening is free for landlords, tenants pay a small fee per pet, and zero if they have an assistance animal. 

Also the seller got the title from the city on a tax sale and can only offer a quitclaim deed so is offering seller financing.  

And finally, is there a more tax efficient state to base the company-i.e.

When you know the buying process, the neighborhood, and how to find the property on your own, and are ready to buy another property: How can you avoid the 2-3% buyer commission portion going to an agent on an MLS listed property, without having to get your license and pay the costs of having a license?

They are paying $825/month.

Should I save and pay it off quickly or would the money be better in my pocket or in stock market? 

When the sale ended around 12:30, the staff of three said we needed to wait to be called up to pay.

He says that he is willing to cooperate and pay all the fees that are mentioned in the lease.

They also pay for title fees. 

There may be other ways to structure it, but yes, FHA would require him to qualify on income but if he has not been earning income as a wholesaler for 2+ years and has two years of tax returns to show for it, it is unlikely he would qualify.