You just need a metro map... We stayed in Cour St Emillon. This is because on Tour they normally have you stay outside of the city as it's cheaper. But it was only a 5 - 10 min metro ride... Get a carnet pass (12 tickets and you'll be set for your 3 day stay).
To get into the Lourve use the back entry... you'll only line up for 5 mins.