The new tenants have paid $80 so far for all screenning, are highly qualified and really want the appartment.

You just have to make a reasonable effort and you can apply your normal screening standards. 

Then I screen the hell out of the tenants and only place people that can pay and won't be aggravating.

If it resulted from your screening it should not be discriminating in any part of it. 

Property management isn't that difficult- you put your time and effort in up front during the screening process and, if done well and you have a little luck, it should be fairly simple after that.

Learn what it takes to screen a good tenant, talk to them and get a feel for them, set expectations, etc. 

I also use the credit check and screening software aspects of Cozy.

What is the best way to remove the infestation, or what is the best way to screen a pest control company?

I signed up for Buildium, the property management tools are good:  I like keep tracking of my leases, leases that are maturing soon, tenant contact info, electronic payments, and tenant screening tools are easy to use and help to keep me organized. 

Moving forward I might start implementing m2m leases and tightening screening criteria and inflate the rents a little more than market to alleviate the trash.