US Immigration from Canada

My fianc and I are about to send off our petition probably sometime next week, as we've been busy compiling everything.
I do have a few questions though regarding not just this petition but the process to ensure I am ready to get going.

I was told they ask for vaccine records, but what do you do in the case that you don't know/have the yellow paper?
And are there any vaccines that are mandatory that i'd get rejected for not having?

Are there specific guidelines on the wedding for the K1, or is it just what the laws are in the state?

Is there any way to have a 'backup sponsor'? I would love my fianc too, but in the event for whatever reason we get rejected for that, am I able to give another form of a different sponsor or would we need to start over from the start? (Cr-1)

Hello! We applied for the I-129f in August and are in the throws of waiting. My fianc is from Canada. At the time, we thought the Vancouver consulate was the correct option, but have since realized we should have put Montreal. Is this something we should submit a request to correct now via USCIS or will we be able to correct this at the NVC stage? Thank you in advance!

Can I take my own digital photo for the DS-160 and then bring 2 professional passport pics for interview?

Or do all the pictures have to be the same?

Do I need to get passport photos taken for the DS-160 or can I just take a pic that meets the requirements and upload that?

I know for the medical and final interview I will need actual passport photos.

Hi there, I'm starting to gathering documents for my K1 visa and am trying to figure out how to bind the documents together in the end. Just loose leave with the name, page number, etc, on each pg, and that's it? Can't seem to find the answer in the instruction packet. Thank you very much!