I'm also returning to the US LOL. Got a concert.
Bet yes to answer the questions;
*Do you mind sharing your experience going through immigration at the airport?
I drove from Chicagoland through the Detroit/Windsor point of entry. So My experience may be slightly different
*Required documents: COPR sheet with the photos attached, Passport, Personal Effects and Accounting document.
I also made and printed out an excel workbook which broke down a list of everything I had, so all the electronics was 1 category, etc.
*Did you went to the kiosk first and then got directed to an officer?
Again as I drove, may be different, but I went through the normal system then was directed to customs office.
*How long do you have to wait? What kind of questions they asked you?
Wait time was around 30 minutes. Was asked to verify my new address, date of birth, full name, and if I had other goods arriving at a later date. Then in my case me and the officer walked to my moving truck, and he went over the list I had and just verified a couple high priority items. Like my 3D Printer, PC tower, and some of my other hobby items.
*Although I will have to come back to the US a week after landing for family matters so I'm still worry how I'll get back to Canada after that haha.
Passport will get a stamp that shows you've landed, bring that and a copy of the COPR when you cross till the PR card arrives.