As you found, a rejected application because of your bad referral means you are stuck with the tenant.Eventually though they will only be able to rent to folks who don't screen, and those are usually the worst places who don't care about bullet holes and pests and rodents and code violations.Don't ever stop your eviction process until they are out of the property and you have keys in hand and have assessed all the damages.

3) Is there a usual or standard amount/percentage for the Option Fee, rent credits, and any other fees/charges?

Do you have a business line of credit by chance? 

You can choose credit only or credit plus criminal & rental history. 

I called a few credit unions local there, and they told me I have to live in the area to be a member and ultimately to take out a loan. 

. $1.1 mil + equity in my property (no liens, and very good credit score)Since I am running a business on my first level of my home, I couldn’t find any financial institution to secure me a HELOC (apart from point.com which doesn’t seem a good deal for me)…apparently, the lenders don’t like mixed commercial/residential type of business (e.g. assisted living).

Being a contractor and being a landlord are real close , I get a security deposit up front for damages that havent occured yet .

What if one persons income/credit score qualifies alone?

This a job is to rebuild 4 fire damaged apartments.  

The few hundred dollars it would cost you to sit down with a competent lawyer is likely to save you a lot of brain damage down the road.