1) Clown loach - mine have just started to do the "pretending to
be dead" act. I have read this is typical loach behaviour, but
is it because they are unhappy/happy/growing up/whatever?

From 6am-7pm, they'll play around the tank, at almost exactly 7pm, they're
sound asleep. Can shine a flashlight at them or whatever and they won't wake
up.
When they were in their 30g tank a while back, they had their home in a log
where they slept. Intro'd a pim cat to the tank, and he claimed the log,
clowns had to move out. Every night between 7-7:30pm, they'd pile one on top
of the other in one corner, on their sides.
I've since moved them to a 90 with lots of hiding places, so don't see their
sleeping habits anymore, but theirs still one that'll put on a show late at
night, around 11pm he'll wake up and zoom around the tank until the lights
go out. As I write this, it's 2am, crazy guy's at the top of the tank
schooling with the Bala's.