Dummy's guide to working with WP MU locally then remotely?

I’ve prowled all over the place and see a wide variety of suggestions, enough so that I’m quite flummoxed or just overwhelmed, so I’m hoping some gentle gurus can help this young jedi out…

The gist of it is, I need to be able to work on and tinker around with WordPress on my local computer. This includes plugin updates, template modifications, and whatever else one does when they’re up to their sleeves in WP (multisite). Then I need to be able to deploy those changes to our live site, which may have had additional stories, comments, etc. posted in the interim.

I will also have a couple other folks working with me on this in other locations, so obviously we will need some sort of distributed versioning (Git? Beanstalk? Mercurial? SVN out due to no distributed model) to track and update all these changes and updates.

One of my major hitches is the databases — what’s the best and easiest way to make sure the databases stay synched up? Since the site will be live, what’s the best way to handle comments and stories that have been posted while the local site was being updated? This is where I’ve been pulling my hair out trying to figure this one out. I want to avoid having to go the route of database dumps & uploading changes if necessary plus it also wipes out any changes on live site in interim.

Where I am stuck is I am not quite knowledgeable enough to execute some complicated maneuvers to do what I want to do, so I’m hoping you can provide some sort of Dummy’s Guide to do it the Dummy’s way if possible that’s the easiest and simplest way, if there is such a thing in today’s world.

For example, I have looked at using Git with Beanstalk, it seems relatively simple, but it doesn’t handle databases.

Bottom line, I’m just looking for a way to make this all happen and as easily as possible with a minimum of fuss for my poor, overloaded brain.

Many humble thanks, Ray