Yeah, I've fixed that wording (guessing I was thinking "upload" and typed "upgrade").
No, that is up to you. (That should be easy: it's in the default filename as you asked.) But restoring to the current platform version should always be fine. It's the odd case of if you downgrade platform versions and try restoring a newer database version. I'm assuming this would be pretty rare, and since you really only have access to the last few versions and these changes are rare in the first place, even rarer to run into this issue. Yes, you'd need to look at the release notes (or ask) to figure it out, but again, the release is likely to be recent enough that you'd remember reading it. This has only happened a few times that I can remember, and again has affected only specific upgraded apps as far as I recall, never totally breaking everything. (Also note that if a platform version introduces a totally new apps or drivers, these instances would also break in that they'd be unavailable if restored to an older platform version. That should be easily fixable by removing the app from its status page, the same "fix" you could use for the former too if you don't mind that approach.)
If you're not sure, matching versions is the best way to avoid this. But again, most of the time you'll be fine.