WordPress MU

I'm currently administering a small network of about 8 WordPresses. I'm thinking of moving over to MU from individual installations because it'd save time with upgrades, etc. Before I do so, I need to have some questions answered. I have searched this forum, as well as the Internet in general, and haven't found any specific answers to these questions.

1.) Can one installation of MU handle different domains and subdomains?

2.) Can sitewide tags be implemented across all sites in an MU installation, even if those sites use different domains? I'm really interested in this feature, as I'd like to have "universal tags" that work across the entire network of sites (not just the subdomain sites, all of them).

3.) I'm considering moving from my current web host to wpwebhost.com and that company states that it'll install WPMU for no additional charge. Beyond that, how difficult is it to get things up and running? I know that's a difficult question, and the answer depends mostly on my skill level. I'm not a total n00b with this stuff, but I'm far from a professional, too.

Any help that could be provided here would be appreciated.

1 - yes, subdominas are given as an option on install (it;s the default) and domains are handled via a domain mapping plugin.

2 - yes, but not the way you think. :) There's a sitewide tag plugin, but that gather everyone's tags on each blog and collects them in a tags blog. There isn't a way to limit tags to pick from.

3 - the install is the hard part. :) You may find a few plugin incompatibilities, but if you've been using WP any length of time, you'll pick up on it.

There's a new menu item called Site Admin which does some global management of the blogs, but otherwise each blog acts as a stand-alone.

Tons of stuff here:
http://wpmututorials.com

Thank you for your response, andrea (and also for the replies on Twitter - I'm now following you there). I'm beginning to see how WPMU seems like it could handle what I need.

However, before I posted here, I sent the same list of questions to sales/support at wpwebhost.com. I received a reply today that said, "One WPMU installation only supports one domain name. You can have additional WPMU installed in addon domains, however they are different entities. So the sitewide tag only can work on one domain (and it subdomains) under a WPMU installation." And this information isn't necessarily incorrect, from what I understand. I could use the Domain Mapping Plugin to map different top-level domains to different directories on my WPMU installation. So, to the outside world, it looks like I have different, individual websites. But they're all living on one WPMU installation. At least, I hope that's what would be happening.

And with the sitewide tags, I'd like users to be able to click on a tag on one of my sites (say a tag called "podcast" on shawnogram.com) and be able to see all entries tagged with "podcast" on all of my sites including those that are on different domains from shawnogram.com, but still running on the same WPMU installation. I believe that, with using the Domain Mapping Plugin, this should work, as all of my sites' tags would be "stored" in one place. Something similar to http://en.wordpress.com/tags/

In the end, I realize that the only way I'll know for sure is to actually get a WPMU installation and give these things a try. My current web host won't let me install WPMU without making what I consider to be an expensive upgrade. But I could still open an account at wpwebhost.com just to give it a try.

I have to go try the domain mapping over there as well, so I'll certainly let you know...

Could be they haven't done it yet, or you need a certain account level.