WordPress MU

I couldn't find an answer to this, maybe I wasn't looking at the right place.

I currently have a wordpress blog for myself and am going to be handling (customizing the stylesheets, installing plugins and widgets, configuring and installing on their servers) blogs for my clients as well.

I want to be able to add and edit content and have access to all of the blogs I am creating for clients.

Is WPMU right gfor me? Do I upload WPMU to my current blog, or how would I move forward?

Just a little bit of direction would be appreciated. Thanks!

If you feel well with WP, have some clue in PHP/MySQL and know basics of LAMP - you can give WPMU a try.
Giving WPMU a test drive on your local PC or some other test environment won't harm, maybe you'll even learn something new ;)
Go get it and try. If you can't manage it - other solutions exist.

Regarding your other question - there's a way to import WP blog(s) into WPMU, search this forum.