cm,
First of all, to put it politely, forget Rail Europe as they're virtually useless in terms of providing a good balance of information. If you want to check schedules just about anywhere in Europe (including France), use the Bahn.de (German Rail) website.
If you want to buy tickets for France, Germany or Italy (and a few other countries), using the Captain Train website is by far the best method. Prices are the same as buying from the actual rail networks, the website is very user friendly and their customer service is excellent.
If you can adjust your Itinerary, I would highly recommend spending at least one night in Bayeux. It's a beautiful smaller town, and as you mentioned there's also the famous Tapestry, and an excellent WW-II Museum.