Wife just received her passport a few weeks ago. Took 6 weeks...expedited service and overnight delivery paid for. .still waiting for her Naturalization Certificate to be returned.
Income is taxed. Assets are not taxed, but might have to be reported to the Treasury Department via an FBAR. I think your questions are beyond the scope of a self-help forum. Good luck on your journey to the US.
I would forward all mail received during that period to a trusted friend or family member who can let you know if you receive correspondence from USCIS. Missing a scheduled interview would not be wise.
The immigration process requires a great deal of knowledge, planning, time, patience, and money. Becoming an A student of the process is a good first step. Good luck.