macOS Monterey Upgrade (Question)

Hi! I just saw that I can upgrade from Big Sur to Monterey.

I haven't actually upgraded from Previous macOS to Big Sur, so to prevent me making any bad mistakes and then needing an in-person conversation to Apple and then send my Mac to repair, I will have some questions: If I upgrade,

1. How long can the average time take, because I might need it during the upgrading process?
2. Will my Mac's files (local or iCloud or both) be deleted so I need to backup them?
3. Is my browsing data, cache, tabs, system preferences (settings) data going to be reset?

I may still have more questions, so the list can continue later...

If you have any answers, please give me a suggestion/answer to this, but if there is an article I can refer to for upgrading FAQ, please point me to that article, thanks (I can't find it yet)!