No, mobs will not spawn in water or ontop of half slabs.
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.
No, the AI for mobs in minecraft has been improved so mobs don't spawn in strange places. You can manually spawn them in lava with that mob's egg.
The only mob that can spawn in water is currently a squid.
Yes, in the Nether Zombie Pigmen spawn on the netherrack but I don't think they spawn on Netherrack in the Overworld.
No, mobs will not spawn in water or ontop of half slabs.
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.
No, the AI for mobs in minecraft has been improved so mobs don't spawn in strange places. You can manually spawn them in lava with that mob's egg.
All hostile mobs spawn on easy difficulty.
The only mob that can spawn in water is currently a squid.
Grass and stone blocks.
If you mean by mob egg-type things, you can't. Only darkness can cause mobs to spawn.
Yes, in the Nether Zombie Pigmen spawn on the netherrack but I don't think they spawn on Netherrack in the Overworld.
You name the spawn egg dinnerbone or grumm
No, there are preset spawners undrground and hidden ones in blocks.
Explore around. passive Mobs can spawn almost anywere on land.
Yes, but the Pigmen and Ghasts won't spawn.