Q1 Why are they called 'uncaught' ... ?This is pretty standard jargon. There are low level routines, each of
which traps the errors it expects. Some trap mice, some trap bears,
some trap bacteria.
Every once in a while, something unimaginable like the Loch Ness
Monster comes along and eludes all the traps. So Mailman sets up a
moat around the castle in a high level routine, and it is the high-
level routine that eventually catches the tricky ones swimming in the
moat, and throws them in the dungeon because it has nothing useful to
do with them. Then it calls the Sherriff (that's you!) to decide what
to do with them.
So "uncaught" is elliptical: it means "uncaught by one of the handlers
for errors we are prepared to handle sanely."
From the "aren't you glad you asked?" department.