Lol I'll try to answer these questions in the order that you asked them.
1) the US version of the watch is preinstalled with the Samsung pay app.
2) I am with CIBC
3) it is only CIBC for now, but select cards is a bit inaccurate. It's all CIBC visa cards. They say select because CIBC also has 2 Mastercards, they do not work yet
4) once your scan your card using the Samsung pay app you automatically get a welcome email from CIBC and you're done.
You do have to enter a zip code. I used the 3 numbers from my postal code followed by 00. For example your postal code is L9M 3C4 use 93400 as a zip code.
I've only been to once place it hasn't worked so far, and even then I'm not sure if it really wouldn't have worked or perhaps it's just limited to dollar value. NFC payments are generally limited to $100. Samsung claims MST payments do not have a dollar limit, but today I tried to make a payment for $113 and it failed. All other payments I've made were under $100 and have been successful. Perhaps CIBC has added their own value limit.