So you're specifically asking for sources and not answers to all these questions, and I want to avoid breaking the rule against just dropping a couple links and leaving it at that, so I'll try to provide a little more information as far as what you're likely to find useful in these books and which of your questions they're likely to answer.

I suppose I'll also add to this preface to say that I'm not sure what level of school this assignment is for- I might be assuming here you have access to a university library (or to ebooks through your university library) otherwise I'm probably just giving you a rather expensive recommended reading list.

To start off with a massive volume, The Weimar Republic Source Book is a great resource to get started on probably all of your questions except the final one (how they recovered). It's a compilation of primary sources, many of which deal with politics, ideology, and class in Weimar Germany but with plenty of sources about the social life (art, music, technology, sexuality, etc) in the late 1910s, 1920s, and early 1930s.

Thomas Childers's The Nazi Voter: Foundations of Fascism in Germany is the best place I can think to turn to for your questions about how middle-class people's lives changed during the Depression in Germany, as well as your "what changed politically" question. There's a lot of statistical methods discussed in this book, which may or may not be what you're looking for, but the statistics-heavy sections are always supplemented with pretty clear explanations on how and why the Nazi party organized its political campaigns the way it did, and how successful it was in each effort. On a related note, I'd also recommend a book that Childers edited called The Formation of the Nazi Constituency, which investigates different social groups/social classes and their support for the Nazi party. Definitely also a great resource for the middle-class during the Weimar Republic years.

Theodore Abel's book Why Hitler Came Into Power is a truly incredible collection of primary sources. If I recall it's entirely comprised of personal narratives from members of the Nazi party in the 1930s about why they came to support the Nazis with no (or almost no) commentary from Abel himself. It's a really fascinating primary source to read alongside the two books about Nazi voters I mentioned above.