What you need to do is have a full account
Go to minecraft.net
Sign in
Go account settings
Change your skin by clicking the 'choose file' button'
and upload your skin
After that your skin should be changed if you are doing an online server, but if it's a LAN (local) server, you can't unless you login
Bukkit is an Minecraft Server Hosting software.
Bukkit is an API (application program interface) that changes the way plugins interact with the minecraft program. Most server mods will use Bukkit instead of attempting to 'hook on' to the actual minecraft software.
You can't
Minecraft commands were first seen in bukkit server. We do not know when the first commands were made for bukkit servers however
There are Bukkit plugins already available to do that on Bukkit Minecraft servers, but they haven't released any information on actually implementing that into the game.
bukkit
wrong bukkit version.
No
you cannot set up permissions in a normal minecraft server. you must have a bukkit server to use permissions. check the bukkit forum for more info.
You can download minecraft plugins from planet minecraft minecraft forums bukkit (for multiplayer) mods for minecraft.com mods for minecraft.net
advertise on the forums
You'll need a plugin to do so.