The Question and Answer section for An Inspector Calls is a great resource to ask questions, find answers, and discuss the novel.
Depending upon where you are in Act II, Gerald is upset because Sheila is in the room and he doesn't want her to hear what he has to say.... he's upset because his relationship with Eva is going to be exposed.
I'm sorry, this is a short-answer forum designed for text specific questions. We are unable to provide students with essays.
I think Birling is attracted to the fact that Gerald's parents, Sir George and Lady Croft, are above the Birlings socially.