The popup info balloon (known as tooltip, FYI), is a standard feature of the HTML language. You can’t turn off that. What you can do though is to remove the title
attribute of the links.
As for the colours of the nav menu, they’re actually an image located in the sprite_h.png file. If you wanna change that, you’d either have to create a new image, or use a solid colour instead. You can use the Firebug plugin for Firefox to figure which part of the CSS code to change.