You are right, the Cadorna station is on Metro lines 1 (red) and 2 (green).

For hotels, have a look at http://www.locanda.it The site is basic, but in English and has all the information you need, including prices. The hotel is small (only 14 rooms), great atmosphere: just don't ask for CNN, TV's are banned from the rooms. If you really want a great last night and are willing to splurge, go for one of the rooms with balcony.

For a more moderately priced alternative, you can't beat Hotel London, located in a small street very near the Duomo (and Cadorna Station). I don't think they have a site. You can contact them by e-mail at hotel.london@traveleurope.it Phone ++39.0272020166. They speak English, but I think the hotel is closed until next week.

Hope this helps.

Flavio