This plugin implements an admin theme which results in the Dashboard looking similar (but not exactly) to how it looked prior to the 2.5 release.
Because I prefer the appearance of the Dashboard in the pre-2.5 WordPress release and I like to see some whitespace and subtle borders on web pages.
Absolutely - they are all in the supplied CSS file.
Not right now but it is something I'd like to do. I am not sure when I'll get to it though. This effort resulted from a project I am working on which exposed the End User to the dashboard extensively and the new 2.5 Dashboard wasn't a good fit (look nor usage) with the plugin I am working on.
wp-swimteam - a WordPress plugin which extends WordPress to allow it to be used to manage a Youth Swim Team. You can find more information on wp-swimteam can be found at on the plugin home page. An answer to that question.
Sure - I make no claims to be a CSS expert by any means. There are lots of people who are much smarter than I and if you know CSS and want to help, let me know. There are a couple things I'd love to figure out how to do but don't have the CSS expertise nor the time to gain it right now.