I did my landing at Point Roberts / Boundary Bay in BC, Canada on May 27th.
1. Just bring all the documents that sent back to us by IRCC, ex: COPR and passport. You don't need to bring any work permit or previous study permits or even 2 photos with you. I don't know why some members even mention these.
2. Border flag pole. Even though I still have a valid US visa, the US border guard still asked me to come inside and gave me an administrative refusal.
3. Very short. Maybe around 20 mins in total. 5 mins at the US border guard office and 15 mins at Canada's.
4. I don't think so. I get off my work early at 12:00pm on a Friday, and still encountered a minor traffic jam at the border. If you want to do your landing on weekend. I suggest you arrive there really early.
5. No, you have to go to a Canada Service office to obtain a new SIN.
The funny thing is that, I felt more welcome at the US office than the Canada one, as the two US officers asked about my experience in Canada, how long I have been here, cracked a few jokes, and then even congrats me, while the Canadian officer who did my landing was a bit unhappy, I guess? he just checked my COPR, pointed me where to sign, and said : "That's it, it's done. Do you have any question?". I thanked him, and he just nodded.