There is none, that's not even cool. Seeing naked pixels are too good for you?
the only jeapordy addon found is linked below to the Curse addon site. It adds some sounds for certain events.
In general all you need for downloading and using an addon are WoW itself and a web-browser to download the addon from a third party site like wowinterface or curse. That said, there are addon-control packages like the curse client, which allow you to download and update many addons from a central program.
I would start by browsing the UI & Macros forum at the site in the related links. It is on the official wow forums and will give you a huge head-start in your addon development.
No, most addons will not get you banned. The only things that addons are allowed to do in game are approved by Blizzard. If Blizzard does not want an addon to do something, they just make it so that addon can not do it.
You will need an addon in order to move the experience bar. It is not a thing that you can do with out one.
NUD = NON-ULCER DYSPEPSIA
Button forge is an addon, you would be better off going to the addon authors help site if he has one, or the wow forums. They will be better able to help you.
No - all WoW addons require registration ($) and the previous addon: WotlK requires The Burning Crusade, The Burning Crusade requires a registered version of WoW.
Download the addon. You can usually find this on the Curse Addons website (listed in the links). Save it. Then move it to your addon folder in your World of Warcraft folder. To find the folder go to your wow folder, then interface, and inside that should be addons. Next time you are at the character screen an addon button will be on the lower left.
Download a wow addon manager like wowmatrix. Google Wowmatrix --- Inside your World of Warcraft game folder you will find a folder called "Interface". Inside is a folder called "Addons". Addons provided on abovementioned websites usually come zipped, with the files in a folder with the addon's name. Simply copy this folder entirely into the "Addons" folder. Make sure to quit WoW and restart it. At your character selection screen, at the bottom right, is a button "Addons". Click it to see a list of addons you are using. Make sure all addons you want to use have a tick in the box, and that the box "Load out of Date Addons" is ticked, in case you installed an older addon. Log into your character, and the addon should now be active.
In order to manually install an addon, first download the addon and unpack its zip file. Everything contained inside the zip file should then be copied into the World of Warcraft\Interface\Addons folder. When you start up World of Warcraft again, click the "addons" button at the bottom left of the character selection screen and make sure that the addon is there and the box in front of it is checked. The addon should now be running properly. If the addon has not been updated for some time, you may need to click the "load out of date addons" option for it to work, but this increases the chance of the addon causing errors.
You should download the curse client and download the addons via that, on my computer the addons automatically go to the WoW addons folder located in the interface section of the WoW folder.