Caen is a college city and thus very active. In summer, tourists (mainly British and German) gather in Normandy for Second World War remains and the Memorial for Peace. Caen is a modern city, four-fifths of which was demolished in 1944 and rebuilt in the 1950s and 1960s. However, some old buildings remain, especially churches.
Trains leave about every 2 h from Paris Saint-Lazare station to Caen and Cherbourg. It lasts about 2 h long and costs 33.30 €. If you book early, you can get tickets as cheap as 15 €. Out of rush hours, tickets cost 22.40 € for people under 25.
Note that the train posting in Paris St-Lazare can be confusing to the first time traveler. The train line number ("la voie") is not posted unil 15-20 min before the departure, so do not panic if you arrive earlier than that (notice that the train will be at a line number near the office "Grandes Lignes"). Look for the train heading to Cherbourg. Caen will not be the listed destination, as it is a stop along the way. Do not forget to punch ("composter") your ticket in one of the yellow machines before boarding to validate your ticket although many trains no longer require that. Check your ticket to be sure. Furthermore, for the regular TER intercity service, Caen will very likely be listed as a destination on the departures board. All Normandy trains out of St. Lazare leave from a "Trains toward Normandy" section, on the upper level, that is well-signed and easy to find. There are only a handful of tracks/lines/voies for Normandy trains, so you shouldn't have to move far once your train's departing track is listed. There are yellow SNCF (French train authority) kiosks both at the entrance to the St. Lazare station and at the departure tracks for Normandy trains.
The bus verts will get you around Normandy easily. Within Caen and its close suburbs, use the bus and tramway network, called twisto.
D-Day Landing Beaches. Caen is close enough to the D-Day sites to act as a base from which to explore the D-Day sites. It is a short train ride from Caen to Bayeux. From Bayeux train station, you can catch a bus to some of the D-Day beaches. On the bus website  there is a map of the bus route to the D-Day beaches. Bus No. 70 takes you to Omaha beach, the American cemetery, and to Pointe Du Hoc. Bus No. 74 takes you to Arromanches beach, the location of the Mulberry harbors. Note the bus timetable as buses are few and far between so schedule your bus trip to take into account the few buses. Also, buses do not run when there is heavy snow, so check the bus website beforehand during the snow season.
The Vaugueux is full of restaurants.
The Rue Ecuyère, near to the Rue Saint Pierre is famous for its bars. If you are looking for a pub, you will find some at the harbour located Quai Vendeuve.