It's generally not possible to apply for citizenship from outside Canada as the physical presence calculator asks you for date you returned to Canada. I am not aware of any exceptions.
It's not a written rule I think, but the system won't let you submit without entering a return date. If you enter a bogus date for the sake, that would be misrepresentation. Get everything ready, and then just travel back to Canada for a couple of days and submit while in Canada.
So, I went to Canada for 2 days. Applied Citizenship online and came back. While Appling Citizenship, I uploaded US Visa details in 'Other/Additional document' section - This is to be transparent of all my visa status. (Note: I also plan to go back to Canada for test and oath as needed)
Now, Should I let IRCC know that my current address changed after applying? Or it doesn't matter?
And If you suggest that I should let them know.. then how? via webform?