You can order an adapter online but you may also be able to buy one locally. If you have an AAA store near you they always have adapters and have the ones that are marked as to what countries they cover. You'll need the general European 2-prong adapter. Bed, Bath and Beyond and Target generally have them as well.
Even when I did this tour a number of years ago all the hotels had hair dryers. Sometimes they are tucked into the wardrobe, most often they were wired in.
Hopefully you've got your shoes broken in! Please concentrate on shoe function so your feet will be happy. There are a couple of long walking days on this tour - Amsterdam and Rome were my longest days at over 10 miles each location so you will want shoes that can hold up to that.
This is a wonderful, wonderful tour! A RS tour guide for another country told me this was his favorite tour because you see blockbuster sights every day! He was right!
Do you have your guide's name yet?