I have lived there on and off for over 3 years and have never seen temperatures exceed 85 degrees, in any part of the country. 

I understand that the electric heat pumps are not efficient at lower (winter) temperatures, which we have a lot of in Philadelphia winters.Are the newer models as bad as some of what I've read online?

Cracks larger than 1/8" inch on concrete,  might be a concern, if they are opening with time (note temperature changes like winter vs summer will affect the opening of the crack, even if they are inside the house just because the expansion and contraction with temperature). 

The amount depends on the temperature, Texas summers can be brutal. 

When the single handle is not used, I suggest that you use a thermometer to measure the hot water temperature immediately after the hot water heater has stopped a heating cycle, by running the hot water at the nearest faucet.

Landlord in chicagoland require by law to provide temperature above 68 degree in winter.

Use the quality soft black kind, it looks better.Keep the temperature of the hot water at 120 degrees.  

It died the last week of May when temperatures were in the 100s.  

I have no idea what the temperature of the market is there.

Heating cables can be one of two types:-thermostatically and/or moisture controlled, when the temperature hits a certain temperature and there is moisture in the gutter (near the sensor) it turns on.