Greetings Marc,
Glad you're making the trip out to France. It should be a great experience. There's actually a lot of WWII era American appreciation in Paris. Franklin Roosevelt has streets and Metro stations named after him and there are various monuments throughout the city dedicated to America for its participation in the liberation of France.
In terms of how to act while in France, I can only give broad advice on this. When dealing with French staff it's a good idea to start off with Bonjour and then I suggest politely asking if they speak English (rather than just assuming that they do). Sometimes it'll be obvious that they speak English, for example, at your hotel. In such cases, don't bother asking. If they don't happen to speak much English, just use very basic terms and hand gestures and I'm sure you'll make out. As a very rough estimate, I'd say the majority of those working in the tourism/transportation services industry now speak enough English to make any encounter painless. About half the rest of the population will also speak some level of English.
The simplest route to your hotel is as follows:
-
RER B from CDG to Paris Gare du Nord train station (exit the train here and transfer to...)
- Metro Line 5, direction Place d'Italie, until République station
You use the same ticket for the RER B train as for the Metro. That article above for the RER B will detail how to purchase tickets.
Here is a
Google Street View of your Holiday Inn at République. Using Street View is a great way orient yourself for your eventual arrival at the Metro station closest to your final destination.
For visiting the Normandy American Cemetery, there unfortunately isn't high speed train service available, although regular rail service does exist. The
American Battle Monuments Commission has good instructions on getting there. Keep in mind that you'll need to finish the journey via cab or coachline.
To purchase train tickets for Paris to Bayeux (closest train station to the cemetery) ahead of time, for delivery to your home in the U.S., see the
Buying TGV tickets article.
Hope this helps. Don't hesitate to ask for further details if you need.
Best regards,
Ben