Can you answer a few questions about the movie Harold and Maude?

Ok so i just saw this movie for the first time today... So was Maude in the Holocaust? Harold looks at her arm and she has a tattoo... Maybe i just didnt see it very well.. And what is the significance of it... And Also, Why does Maude kill herself at the end? I dont get why she needed to die.., Oh and Did Harold and Maude have ? Becasue they were in bed together and they didnt have clothes on but thats kinda sketchy....