Typical containers are all welded. They don't break down or fold. Keep in mind containers stack on top of each other, being able to tear them down or fold would compromise their strength.
I doubt it, they need to withstand rain, snow and seawater, possibly refrigeration for a good share (I’m thinking about Apple products which are not supposed to go beyond 35°C - How do we manage sun exposure between the tropics?).
Surely it's "35C" only when powered on? Which is still a weird figure which is probably wrong because how are those products going to work close to a human body which has a default temperature of 36C (when not excercising, when not in the sun, etc.etc.)?
Your core temperature is that hot, but your skin won't be (unless you're in a desert or something). So you'd never be able to transfer that temperature to a Mac.
In the sun your skin (even under some clothes) can be much higher temperature than 36C.
They put those containers lower down, out of direct sunlight. This costs slightly more, but also means they're less likely to fall off in a storm.
It's 45°C for storage. There might be a higher limit for shipping.
I thought they could be folded flat? Maybe that was just some special models I have seen, though.
The vast majority definitely cannot be folded or otherwise disassembled. They are welded together as simply and with the fewest number of parts as possible, while complying with international standards.