Similar situations for temperatures, moisture levels, soil types and elevations.

When it's cold outside, measure the temperature of your exterior walls with an infrared temperature gun.  

I doubt if we have the hardness you recorded but yearly preventative maintenance of any system is imperative to longevity.Given the precarious attic location I would definitely review the obvious advantages of an on-demand system.I have also designed a simple fix for the 'cold water sandwiching' issue that plagues the on-demand systems with feed water temperature fluctuations common in colder climates. 

I don't think it's a substantial amount of heat (temperature) on the backsplash, nothing it can't handle anyways. 

It is a simple fix - just sand and refinish the floor and make sure temperature in regulated in the summer (can be a challenge while renting).  

Many inspectors don't open the furnace cover to actually look at the coils so you may have to request it or have HVAC company look at it (often times they just do the temperature readings/differentials).

Seems like with something so important/specific as needing to keep the heat above a certain temperature to avoid the pipes from bursting that there would be a specific clause in the lease that addressed it and spelled out the minimum temperature that needed to be maintained. 

It was stuffed so full that the airflow was cut off and the fridge was almost room temperature.

I recently did 1/2 thick travertine in a small bathroom & regretted it as it did suffer hairline cracks regardless of the solid thick backerboard/cement base its just the nature of the stone & more likely the temperature extremes we had last winter.

The shades, doorbell, temperature and more can be controlled by voice or device.