No, not that i know of. I've heard a few people say they can but i don't believe it.
Chat with our AI personalities
In Minecraft Classic, mobs can't spawn, so they can't exist naturally. If you play the Survival Test, and when mobs spawn there, you can save it and open it in creative mode so then the mobs can stay there. However, in Minecraft Creative Mode, mobs can spawn, but they can't hurt you because you have no healthbar.
Lots of stuff. Redstone powered lamps, zombies breaking down doors, AI for all mobs (makes mobs smarter), and many others
Right click on them
You can download mobs minecraft comes alive
No, mobs will not spawn in water or ontop of half slabs.