What is the significance of Mrs. Joe’s death? What is surprising about how Pip feels about his sister now? Why doesn’t it bring Joe and Pip closer?

While the funeral takes place in Chapter 35, I would say that the answer to your question is pretty much from the book as a whole, not from any one passage in that chapter.

The reason that his sister's death doesn't bring Pip closer to Joe is that Pip is not really good enough of a person yet. When he became a gentleman, Pip started trying to forget where he came from. He feels that Joe is a reminder of his past and that past is something he is trying to forget.

At this point in his life, he has not grown up enough to realize that Joe is a good person even if he is poor. So he keeps snubbing Joe even after Mrs. Joe dies.