"Do you smoke? I'm glad to hear it, a man should have an occupation of some kind."
Lady Bracknell is asking Ernest a series of questions to determine if he is worthy of marrying her daughter. One of them is if he smokes and she is glad to hear that he does as she considers it far more important than it actually is.
"To lose one parent, Mr. Worthing, may be regarded as a misfortune. To lose both looks like carelessness."
Lady Bracknell cracks down on Ernest while asking him questions about his family to find out if he is worthy of marrying her daughter. When she discovers he doesn't know where his parents are, she has a little less sympathy than one would expect.
"I never travel without my diary. One should always have something sensational to read on a train."
Gwendolen says this to Cecily when comparing notes as to when Ernest proposed. She holds her private life to be in very high regard to the public, and considers her life extraordinary to the degree that there is very few other stories that would be of more interest.
