My kitten started doing this recently again too..
I haven't really got to the bottom of why he does it, but it happened about 5 days straight, now it's stopped again.
It's as if he just does it to mark his territoy kind of?
Anyway, as for the overnight meowing-our two done that too.
Infact, the carpet on the other end of the bedroom door is ruined because they HATE closed doors hahaha.
I just eventually let them in and it's not a problem as Tom's stopped peeing on the bed, only problem is 3am and Tilly decides to walk across your head haha and pounce on your feet.
Good Luck
Sarah xxx