Hi D.B.e.r.,
first of all welcome to Italy: hope you'll have a nice stay!
Just a short note about the Opera infos.
I am quite familiar with that so I can give you some good advice.
You can book almost any kind of ticket using a popular website (
www.ticketone.it): you can get tickets of concerts, football matches, and opera also.
The only Opera theatre which does not use Ticketone is, of course, the most famous: Teatro alla Scala.
Also, bear in mind that La Scala Theatre is actually under major repairs and for this reason it has been moved to another theatre built last year in a new residential area. That's not bad (there's a little screen for each seat so that you can see more particulars and read also the subtitles of the opera which you're listening).
La Scala has a web site but it is not exately for those who need to get a ticket at the last minute like you. I'd rather suggest you to go directly to the main ticket office.
If you're operating from MXP just take the Malpensa Express train to Milan Cadorna Station: from there you have to take the subway (tube): take the red line and get off at Duomo station. Inside the station (the mezzanine) there's the main ticket office.
I believe this is the easiest way to get what you want.
Hope it helps...
Good luck with your job with Livingston and..please, if you see that there's any right seat available, let us know!
CIAO !