Regarding Greg's comment, I have not yet gotten around to setting up anti-spam, but it is on my list.
Regarding Ian's comment, I have also not yet added a cert for the AutoDiscover vdir. I only have one for the owa vdir. I don't believe I get any errors or warnings because of this, though (at least, I don't remmeber seeing any). I know I don't have free/busy yet because I can't connect to AutoDiscover. I agree setting up a cert is a complex process, and that is something that is being looked at for simplification (certs are pretty complex things to begin with, though).
Regarding Dani's comments, I know I should take that to heart, but I did recently install Expressions Web right on the Exchange machine. Fortunately, that didn't seem to break anything.
Note: I will post an update to this blog in a couple of months and let everyone know of my further adventures in administering Exchange. Also, several others in the team will likely be posting their own experiences soon, so stay tuned for that.