fil the form online (pdf fillable) print it, sign it, scan it and upload it
Photos: https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/photos.html#immigrant Check out this link, photos are very easy to do. What I did, I took a picture with my Iphone(following all the requirements) and then use the tool to crop it and uploaded it, I would suggest to take passport style photos and keep them with you (I don't know if she have to take them to the Medical)in our case, everything was digital,, no printed photos.
I was only asked about the transcript from the year that was indicated on the I-864, but I had the other transcripts ready, also, before the beneficiary was approved, I was asked to upload w-2's from the most recent year and check stubbs from the current year
It is correct, do not need a translation if they are in english or the language of the country
This is my (recent) experience with NVC.
I wish you well