Any advice or helpful tips while in Europe?

Take a power converter so you can plug in personal electronics. Tons of places to see. Not sure where y'all are headed but stay in groups and you shouldn't have issues. Not sure about phone/wifi. We had land lines when I was there.

Learn to speak some of the language in the countries you want to visit and think about a translator program for your phone. I don't trust them completely, but if you know a few word, it helps to get around. Yes, English as a second language is very common in Europe, but the locals like it if you at least try to speak the local language.
If you are going to try to see a lot of Europe, Eurail passes are relatively cheap and you can buy packages that allow so many days of train travel. Rail service is very good in Western Europe and will take you at least close to most major attractions.
Check the customs in the country you are traveling. Someone already mentioned that tipping is not universally accepted, so ask around before you tip.
Don't hang out in the tourist and or Military hangouts. Try the local food, talk with the locals, drink the local wine and beers.
Western Europe is relatively bike friendly and the Rail service is used to handling them. There is an small additional charge in some countries, not in others. The parts of Europe I've been in around Germany, traffic reminds me of driving in New York, so if you aren't used to riding on city streets, you may want to leave the bike at home. If I were taking a bike, I would probably invest in a folding bike and a bike bag. Eurail doesn't charge extra for those.

Forget wifi or data usage in most areas but get out and see the countries!