How do I use Firefox?

I recently downloaded and installed Firefox.  After using it for a while, I decided it's okay.  However, is there some way to change Quickkeys and stuff?  I keep hitting "S" for "Save As" when I right-click an image, since I'm used to IE, and it keeps wanting to set the image as my Desktop Wallpaper.  So, how do I change key configuration?

Also, I found the place to empty out the Download window auotmatically, but is there some way to CLOSE the Download window automatically?

>>2
See, the thing is, I'm also used to hitting "A" for "Save Target As..." like when I want to grab an image off 4chan without opening it up, or grab a torrent off a site without launching it right away.