The passport bio page is her proof of citizenship. You're all set.
I thought so, but then they listed them separately on the checklist, so I wanted to make sure.
You've done all that you can do for your driving record. Don't worry about it. If YOU can't obtain it, neither can UKVI. (But do keep your full disclosure in your application!)
Uploading does tend to also be difficult. It's my understanding that the system logs you out every fifteen minutes, even if you've had constant activity. So you log in, upload a few pages, get logged out, and repeat. So if that happens to you, it's normal. (I'd probably just ship all my copies to NY.)
Yes, after the people at the Michigan Secretary of State failed to find me anywhere in their systems with my full name (and I have an unusual spelling for my middle name), former addresses, birth date, social security number, and passport, I doubt UKVI is going to find more. In any case, I disclosed everything I knew in my letter and in the online application. I've been honest.
I uploaded one document last night as a test, and it went up fairly painlessly. But I've probably got 200 pages of docs in total, and it doesn't let you see what you've uploaded to confirm it. I'm going to work on it a bit today, but I have a feeling I'm sending everything to New York. I hate to trust someone else to do it, but I'm assuming they have a better system to work with than VFS website, and I've pretty much had my fill of this process. It's exhausting. LOL
EDITED TO ADD:
How have most people organized their documents to send to New York (or Sheffield in the past)? Should I buy a folder with labeled sections? Are clips (not staples, obviously) recommended to separate documents within sections? Do people still print a Table of Contents? I want to make it super clear and easy for person/people scanning it to reduce the chances of missed documents.
Thanks!