Of course your 10 times more likely to buy music, because your looking for it. But I find it hard to believe that if you pirate music you are more likely to buy the album. I understand the "try before you buy" thought. But there are easier ways to preview music than just pirating it. There is Itunes, Amazon, and a ton of other music services you could use.
I agree, I would expect the same behavior, but I don't think that justifies to activate a menu on a mouseover. Nobody would like an operating system that triggered menus on mouseover. It's just to easy to trigger on accident. I know I'm in the minority on this subject, because most sites do use that technique. Only site I can think of that doesn't is google (the more link off the homepage).
Why are they all activated on mouseover? That doesn't make any sense to me. IMO I think that mouseovers are only good for displaying tooltips or something along those lines.
I think when choosing b/t fixed width and fluid depends on your content. But don't get caught up with this, you'll always have arguments for either sides. It doesn't matter which layout you choose (as long as it's readible). What really matters is that you have good content.