Yes
The only way to do that would be to install a mod to make it eternal day.
If you go near them they blow up. You can kill them with a sword. They spawn only at night or in caves; Somewhere dark
The only way to spawn herobrine in minecraft is to use mods as you cannot spawn him in vanilla minecraft.
No mobs will spawn on peaceful, you may hear noises but they will be effects even on peaceful. the only entities that spawn in peaceful (not including the nether or the end) are players and animals unless, in the end or nether.
The only mob that can spawn in water is currently a squid.
You can't, they are only spawned naturally. You can, however, use a spawn egg in creative mode to spawn them.
Only is you have Mo' Creatures and (MCEdit?) installed.
Minecraft seeds only control the landscape. The creatures spawn randomly.
If you mean by mob egg-type things, you can't. Only darkness can cause mobs to spawn.
slime? they are only in selected chunks and only spawn deep under ground.
You won't, you will only spawn on the main level.
There are no cities in Minecraft as of yet, only NPC villages which spawn naturally in the game world; cities must be built by the player(s) of Minecraft.