General Question About CSS And Scripts

I have a few questions about some of the features I have seen on other websites, if anybody knows the answer to any of them feel free to reply to this post.
First off: I noticed that some sites when you hover over the button the color of the button will change darker or lighter or different color all togather, Is that done in CSS or Script or is it something new that is done some other way. Can it be done is Zen Cart?
Secondly I am thinking about using the CSS Flyout Links in the Header, Is it possible to have the links display horizontal instead of vertical?
Thridly, I want to use the right sidebox but instead of having it enabled all the way from top to bottom, Is it possible to only enable the right side box for two boxes instead of the whole column. I want to use the area on the right for description and site content instead of just leaving it blank when there are only 2 boxes enabled. Is that possible in Zen Cart or I have to code the boxes in to the center box and then float them to the right?
Lastly, what is the easiest way to make the active link have a background like the hover feature? I have tabs in the header and I want to have the active link highlighted.