Can you leave it submerged permanently? I've seen a lot of reviews that
praise the portability and such, but I can't find anywhere that says you can
leave it in the water-butt and forget about it.

Also, the Hozelock ones are advertised as "compatible with aquapods and
drip-feed systems", would I be right in assuming that for this to be the
case, I'd need to physically turn on the pump to feed the watering system
(as opposed to it automatically coming on for watering via timer)?