All hostile mobs attack you even when you are in creative.
It's spelled correctly:
http://minecraft.gamepedia.com/Ink_Sac
All hostile mobs act as if you're in survival and they will attack you.
Basically any new mob doesn't make noise: including the villager!
When I died I spawned in the air and fell, thus losing about 3 hearts.
This is part of the unadvanced AI of the Villager and I doubt that it is a bug/glitch.
Yes, some trees also spawn near the ground and is only 1 block of wood and the rest is leaves!
Furthermore, you can't climb over the leaves as you would the traditional blocks in minecraft (you would have to manually jump)
Yes, when you swim in the water the lighting flickers!