Yes, you must inform the visa office about your new mailing address. Do use the Web form on the IRCC website (Case Specific Enquiry) for this + for the change in your employment status.
BTW applications from Japan may get processed in 14 days (estimated time). So you may not have to send a CSE after all
Yeah. I have a feeling that my travel history and plane ticket purchase as well as itinerary helped. Fortunately the documents were mostly self explanatory.