Very new to BP (so be gentle).

Other contractors - What are your thoughts on putting a moisture barrier between the subfloor and the LVP?

Global warming is irrelevant, you can't both blame moisture (hurricanes) and lack of moisture (draught) on global warming.  

I previously discovered some condensation related moisture under the counter and thus considering switching it out for a tankless water heater.

Yes I am still new, so please be gentle if I am being really dumb here.

Chances are something is happening in the unit above causing moisture to build up. 

Maybe even an offer to help the move out the items is a gentle way to broach the issue.Second, if the family had issues, no clear plan, or I suspected I may be left with debris, caught up in an argument or family squabble, or there was a lot of damage.

Be gentle, I'm new. hahaThanks,Trent

My inspector found some moisture staining on one of the walls that the seller said happen a few years back due to a heavy rainfall in the basement apartment, but seller had his handyman make sure that the water drained away from property

The reason it is so low is due to several factors, including:The construction necessary to survive in the Mojave Desert.The lack of moisture and no hard freezes.The criteria we use to select properties."