There are several components to keep in mind, none are too complicated.Provide a Purchase Option and a Lease Agreement as separate documents, if they dont pay rent, you can just show the lease agreement to the courts (without showing the Purchase Option and complicating the eviction).

Remember: cheaper doesn't mean you'll make more money.Start by going to www.narpm.org to search their directory of managers.

Should I keep negotiating it or this is a good deal?  

I mean i think you answered your own question.

OR should I keep my original plan and section8 it. 

You'd be surprised how many people don't understand what being a co-signer actually means. 

I tend to get frustrated when I keep telling people that you can buy large multifamily with 0% down.

It's advised to keep cash in reserves for vacancy and maintenance so 70% down payment might give you enough cash flow and you have some reserves.

Due to horrible, and I mean horrible property managers in the area (the one known as being the best admitted to me she recently had an employee steal over a million from landlords and she didn't think it was her fault), I decided to hire a family member full time to start managing properties for me. 

This way, you can easily allocate expenses to the appropriate property when making purchases with your Lowes account or other accounts.You can also create separate folders or digital files for each property/entity to keep track of receipts and invoices.