An ounce of prevention is worth a pound of cure. 

I'm worried our only option will be to cut through the wall and duct in the unit below to access the clog.

This prevents the seller of going behind your back and selling the property to anyone else. 

Tech helps create efficiencies and prevent errors.

Aloha,Our rental agreements are pretty clear that tenant is responsible for repairs or service due to misuse, or damage caused by tenant or their guests, including clogged drains attributable to the tenant.

I think we are going to settle at 5-6% as a new normal for rates because it's low enough to encourage activity and high enough to prevent total stupidity from reigning.

This fear could possibly be preventing you from making the optimal choices.

We were able to minimize most of these big  ticket expenses but every now and then we'd have a pipe get clogged or an AC unit go out.  

Took longer than I wanted because I had a lot of other personal things going on that prevented me from being able to get things done as quickly as I wanted to.

If so should be fixed to prevent animals.