Don’t have much experience with odor issues, but sometimes enzyme cleaners work well because they actually eat and dissolve the organic materials.

As will construction materials, and original construction workmanship.

Or is it better off to go with a private contractor, and just pick out the materials myself?

I've sent you a connection request so I can send you some materials on that topic.

I would look around at other rentals in the area and see if they allow pets, another thing to consider is what materials are in the house, example flooring, is their carpet or laminate where the costs of cleaning or replacing them worth it.

To make a long story short, last year (fall 2018) we had hired a contractor to build a garage, and materials that were paid for and "ordered" never showed up.

Nothing in the licensing study materials and testing will teach you anything about real estate investing or wholesaling. 

My brother-N-Law wanted to get into real estate with me so he helped fund the deal and pay for the materials needed.

The confidentiality obligations of this agreement shall remain in effect for a period of one (1) year from the disclosure of the Material to you.

I just re-wried a complete 2 story for about $2500 in materials ($$AFCI breakers are the killer), completed & inspected to code in a week of half days.