No, I want to know exactly those things, but I doubt the Tom tom will work since that is just a USA app. Of course the other is run by google maps and those will work in europe since they have the iPhone there.
If you mean the Google Maps app, yes. However, Google Maps needs a data connection to load the maps and if you're with AT&T, roaming charges in Europe will be expensive. If your iPhone is unlocked, you can easily get a prepaid SIM card with data that will work well for you. I did this to get around Spain on a trip earlier this year.
Or, you can get one of the turn-by-turn navigation apps for Europe that are in the app store now (by Sygic and Navigon), which load all of the map data on your iPhone and don't require a data connection. You can then keep your iPhone in airplane mode to avoid data roaming charges – this will disable the GPS receiver, but you can at least browse map data in these apps and still plan routes and view the turn-by-turn instructions.