Turn off Preaker to Water Heater?

I would turn off the water heater when I was not there.

Some utilities have special plans for vacation properties they do save some bucks here.

Some breakers are rated to be used as switches, but residential type usually are. Doing once in a while is probably okay. I put a switch on my cottage water heater, and I put it in a more convenient place than the circuit box. Assuming access isn't a problem it is simple enough, but if I had it to do again I would have used a relay and put the switch at the front door.

Turning off all the power is fine, but probably unnecessary; I don't even do it in the winter when I won't be there for several months. (If there is an electrical problem, I would rather fine out when I am NOT there...)

You mean, "residential type usually are NOT."

"residential type usually are" should be "residential types usually aren't" That's completely different, never mind

As long as there is sufficient heat in the dwelling to prevent freezing you needn't drain the lines. If not, you should drain the lines, water heater and toiled tanks and add RV anti-freezed to the sink and toilet traps.

Don't forget to trun off water to washing machine

We turned off the water to the whole place, and set the electrical heat to OFF, which means it will still trigger if the temperature hits 40 degreed F. Its an apartment building so I don't see that happening.

Turn off the WH, why pay to keep it hot. Better yet get a gas tankless you will only heat what you use. Turn off water at the main a leak could ruin your place , at 5 gallon a minute you would leak 50000 gallons a week, enough for a big swimming pool.