Welcome to the site and to WoW, Triskk.
For help on installing addons, please see our Help & F.A.Q. page:
http://www.wowinterface.com/forums/faq.php If you need further assistance, there is this stickied post as well:
http://www.wowinterface.com/forums/s...ad.php?t=14762 and this one if you use Vista:
http://www.wowinterface.com/forums/s...ad.php?t=14650
Auctioneer can be found on this site, and your saved data should still be intact, as it is stored in a different location from the addon you deleted. The full suite from Cosmos was discontinued, but you can still find several mods from the package available separately on this site.
If you wish to search for a specific addon, you can use our Find page:
http://www.wowinterface.com/find.php
If you wish to browse through all of the addons on the site, there is our AddOns page:
http://www.wowinterface.com/downloads/index.php
To get you started...
Auctioneer:
http://www.wowinterface.com/download...neerSuite.html
Map addons category:
http://www.wowinterface.com/downloads/cat24.html
Feel free to post again in this thread if you still need further help or have more questions.