If you mean for the Bukkit Server, then no, but there is a really good flight mod packed into this one called "AdminCMD". The dev is trying to make it more like the single player flight mods. His fight mod may bring noclip with it in the future.
Many mod developers do not charge for mods however some fee's may be charged if a bukkit plugin needs to be specially coded however it is choice of the coder how much they want to charge you.
You can't respawn the Ender Dragon in Minecraft without some kind of mod. Single Player Commands and the Essentials Bukkit server plugin can both be used to spawn mobs.Whatever you do, don't spawn it outside of the End, unless you don't mind your world being bombed.
Yes Or any other server mod(canary,hMod etc.)
It depends on the Minecraft server and what plugin the server is using for factions, sometimes typing "/help" on a server will give you the command syntax (what is required for each command). Alternatively if you know what mod they use, Google search for the plugin/mod and find out.
You cannot craft a mailbox without a mod (modification) or a server plugin.
The command to do this is /me is away from keyboard or /me is afk in vanilla Minecraft. You'd need a mod or Bukkit server with plugins to do so automatically if someone is away for a certain amount of time.
well, 1st of all, don't get close to them. You can download a certain mod on your online multiplayer sever. I use bukkit. you can get some sort of mod to stop creeper explosions. hope this help.
There is a plugin called World Guard that can do both. Look at related links for its download page.
depends, if your server is basic you'll need modloader for mp and other plug ins installed in the minecraft server jar (others should be metioned with the mod, and you will also need the mod in singleplayer installed, that should work, for bukkit it should be the same procceses for some for installing mmods in the jar and adding plug ins.
a mod where you can fly a plane on minecraft so get it
Minecraft doesn't have an official best mod.
Nope. You HAVE to download a minecraft mod to have it.