A cracked ceiling is replaceable, a tree isn't. If he is looking for an excuse, this isn't a good one IMO.
Is the crack straight along a possible seam? at a given fixed distance from a wall, like 4' or 6'? along a joist?
Could be that one of the elements is burnt out, the anode rod defective or the thermostat not functioning properly. I'd look into those two easy possibilities before tinkering with the controls.
Hmmm Tough question because where you live I'd say that growing grass is pretty much a shot in the dark type of situation and beyond that, I'd also say doomed for failure. I say this because you may well be in that transition are across the middle of your country where it is too hot for the...