ENvironment Map Help needed

alright, how do you alter HDRIs for backgrounds? i got a free one, i’m having nothing but trouble trying to dfollow tutes as what i get just doesn’t match what i’m reading/watching.
here’s a cut down, basically my World setup and a test plane/box, and the preview version of the image as the actual images are 3k and 8k.

i’ve been trying to move and scale the image to fit appropriately in my camera, and the bugger just will not move sensibly as it does, eg, in this tute: https://www.youtube.com/watch?v=EHnMRDvQeEg [at about 16min in]
also, this said to set the HDR to “sample as lamp” to cut noise but i’ll be buggered if i can find where that setting is?

It’s been renamed to multiple importance sampling, found in the material’s Settings panel.

Edit: Here is the wiki page on MIS.

As to the mapping - http://www.pasteall.org/pic/show.php?id=104083