Chevrolet Cruze head gasket ("A/C off due to...") root cause

Background

I have a 2011 Chevy Cruze with the “Eco” engine that I bought used, May ’18, with about 99,000 miles on it. Seemed to run fine until mid-December, about 107,00 miles, when some hose started leaking and I noticed a lot of vapor coming out of the engine compartment. I drove it to the first shop I passed after noticing the problem (“All Auto Service“, garage of a BP gas station) and had the hose replaced.

Then in mid-February, I took it in for a drive-through oil change (Valvoline). They noted that the coolant level was low, so they refilled it.

About a week after the oil-change, at about 108,000 miles, I started getting messages “low oil pressure” and “A/C OFF due to high engine temperature” randomly during fairly short drives. I took it into a dealer service department (that is, a Chevrolet dealer; not the one I bought it from, but the closest one to my home, and I had bought another car from this location before). They diagnosed and replaced a leaking oil cooler, a leaking “lower transmission cooler line”, a leaking “coolant hose [] (from surge tank to water outlet)”, a faulty coolant surge tank cap, and the oil pressure sensor (“faulty internal seal”).

I picked the vehicle up, drove it home, driving later that day or the next morning I got “A/C OFF due to high engine temperature” again. I took it back to dealer service, this time they found code PB00B7 “engine coolant insufficient flow”. They decided it must be the “thermostat heater with integrated thermostat and housing”, so they replaced that.

The next morning I got “A/C OFF due to high engine temperature” again. I took it back to the dealer service department again. They’ve had it a couple days now, taking the head off to look for a bad head gasket or cracked head.

Question

I’m trying to figure out why all those components failed at roughly the same time (and whether I really needed/need to replace all of them); or could some of them have been leaking for a while, and not really causing trouble?

Could a bad head gasket have lead to the sensors and hoses failing quickly? Or could low coolant from the original leaking hose, or the overflow tank cap, have damaged the sensors and hoses?

In the weeks before the oil change, we went through a spell of record-cold weather, and I parked the car outside in it; could that have caused or worsened the leaks?