Judy,
Your Itinerary is a bit "busy" with a lot of two night stops, which will only leave about 1.5 days for actual sightseeing in each location. Unless there's something specific you want to see in Milan, I'd probably drop one night there and add to one of the other locations (Florence or Cinque Terre).
I assume you've already purchased flights for the trip? I'd suggest a slight change in the order, for better efficiency. There will still be a few longer travel days but you might consider travelling Rome > Orvieto > Cinque Terre > Florence > Venice > Milan. The shortest trip from Orvieto to the Cinque Terre will still be about five hours (with at least two changes), but it's not a difficult trip. When checking times on that route, I used La Spezia Centrale as the destination, since you didn't specify which of the five towns you'd be staying in.
For your stay in the Cinque Terre, it would be highly advisable to get a room booked SOON, as that area is very popular and it can be difficult to find accommodations there at times.
Regarding local tours and cooking schools, I'd suggest having a look at the RS Italy 2016 guidebook, as I believe there's information on both those activities in the book. I often find it a good idea to pack the book along, as it's a good source of reference when planning tour "on the fly".
If you haven't used trains or other public transit in Italy, there are a few potentially expensive "caveats" to be aware of. If you need further information, post another note.