Hi Mike,
I believe that you should not necessarily call it an "application fee", but rather a credit and background check fee. The typical amount is $20-30. I picked that up at the City of Milwaukee landlord training that is held a couple of times a month. Check it out on the city's website.
In regards to the marketing, I would use a combination of both. Yard sign are good for populated areas, but you may get a bunch of unqualified individuals calling/texting. You can simply screen them over the phone and ask the pertinent questions right away that fit your ideal tenant.
There are many good services noways that help screen tenants. I have never used one personally, so do your due diligence, but I am sure that most reputable companies are comparable.
Walt Buchanan of State Farm is a great agent. I would also recommend Sherry Yusef of American Family.
Appraisers? Can't help on that one. Sorry!
Shoot me an email if you need more info.
Regards,
William