Do you charge application fees?

Based on the below limited information, what is it worth?

"Must have 3X monthly rent in pre-tax income and a 650+ credit score"  In addition, I have the applicants pay the $30-$40 fee to have me use the following website "https://biggerpockets.mysmartmove.com/" to screen their credit. 

Or generally speaking, prices in the area went up, due to limited supply and high demand.With the Amazon HQ2 it won’t be much different.

I used to be the office manager for a construction company and always joked that when we accepted applications, it was "felon day" at the office.

For me personally its a tool, and you have to know when/how to use it and what its limits are. 

There are limits, etc or special requirements depending upon how many replacement properties you identify.

At this juncture, I would review the tenant's application and tenant file.

Regarding the second question, concessions are allowed but often limited and generally only apply toward closing costs.

If you want to avoid ending up in court everything you say must be very limited.