For their upcoming renewal, I would like to draw up a brand-new lease and add an updated pet policy so they will know my rules if I give written permission (they have asked us to consider a dog- which current lease says no pets, but considered case-by-case). 

For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

Hello folks in Georgia / Atlanta,The Bigger Pockets Book On Rental Property Investing provides access to a comprehensive list of 34 forms that would be useful to a landlord including things like a lease agreement, application, late rent notice, move-in-move-out agreement, estoppel agreement, tenant phone questionnaire, pet addendum, etc. etc. etc.  

We are going to allow pets, so we did nothing but several good coats of wax on the hardwoods.

You can run an ozone machine for a bit while no one (including pets, but assuming they have none) are in the house.

For most parcels this means removing trash, bush-hogging, tilling and planting a food plot to attract wildlife, posting no-trespassing signs, etc.  

There's a real good chance that the lease requires them to do several things: upkeep on the unit is a big one (damage to property), weeds outside and landscaping (which encourage pests and insects to inhabit the property), pets authorized or not, additional tenants on the property that are not on the lease.

The pet odor.

I have a dog myself and, therefore, will have to allow pets in other units as well. 

Hire someone professionally locally to work for you and oversee manage the project (a construction manager).Some examples I can provide having worked in the construction industry is - soda bottles filled with urine in the walls, food thrown in the walls, throwing coffee down duct risers, sheetrocked over outlets providing fire hazard...