(for eg: grading of the house outside, rot, exposure to moisture...)I am worried about the long term expenses that come along with it?

Most people think they're OK taking out the little roots and not messing with the big roots, but it's actually usually the opposite - large roots just stabilize the tree, while the small roots are the "feeders" that provide nutrients and moisture.

Steel, tile, slate, etc are all significantly more expensive, and decking issues beneath the existing (due to moisture, etc) will also significantly increase cost.

Also, your "inspector highly suggested getting a termite bond"... is there reason to think there's termite/moisture issues with the property?

Note that this is ground level unit and there was a theory at first that external moisture is causing it so we tried to work with the HOA. 

Recommend repairs to reduce moisture damage.

If specific concerns are raised (structural, moisture, electrical, etc) then the engineers or other specialists/trades are brought in for a more thorough examination.  

They need to get in there to check the moisture in the walls right now.  

The advantage to this is that the fan can continue to run even after the tenant is out of the shower and continue to remove moisture from the room.Anyway, that's just a few ideas.  

The subfloors are typically a composite material and any leaks or moisture inside can rot them quickly and they crumble.