20C - Is that considered "cold pressed"?

Exactly it's "cold pressed" for a better quality.

And how much different was the process in the "old days", before electric machinery?

This is very interesting but I did not live this time.
I've seen only some handmade machines in old oil mills.
What I know is that the process was the same, just as today's electric machines, replaced them with hand-held machines that were human-or-animal driven.
I recently learned that it still works, an old oil mill with the old way of producing olive oil.