I'm so lost, just reinstalled WoW with the new Wrath expan.

I downloaded auctioneer, questhelper, and im totally lost.

First i extracted them to my WoW/interface folder - correct?
Then when i open WoW, where do i enable them? didnt there used to be an addon button in bottom left corner of login screen???
And thirdly, once thats fixed - does either of those two addons have the autoloot? (for any item, not specific ones)

the correct path would be i.e. wow\interface\addons\auctioneer

you can set an option in the interface options so you always loot all items automatically