1. You don't need to provide formal proof like tax returns that your income is such-and-such, just that you will be able to support, and there is no specific minimum income level required. Choose whatever documents support and are easy to understand, incl eg savings and income/revenue, contracts, etc.
2. Just my opinion, put address B and as you suggest, a short explanation that in previous file you put official address per her passport. But in this application, most important to put factual address of where she was living (even if periods separate from you). (Note I believe you should have put actual domicile in previous app, but explanation likely sufficient)