It's Over!!!

I finished the book and I'd say that it had a relatively happy ending. Pip meeting Estella was a good way to finish with Pip getting the girl as I previously stated. Magwitch died which was no huge surprise, but it still was somewhat shocking. However, Orlick being a giant mastermind behind killing Mrs. Joe and swearing vengence on Pip. I have one question though. What is up with Joe marrying Biddy? Joe has to be like 40 and Biddy is around Pip's age. That caught me by surprise. I liked how Dickens made Joe successful at the end. He's learned to read and write, he has a wife, and has a more gentlemanly appearance. I'm still confused about one thing. How did Orlick figure all of this out? Dickens may have explained it in the book, but I didn't catch it. I liked how Pip had to return to the marshes where he first met Magwitch. I thought it was nice how Pip returned to the original place where his story started.