1. Yes, it's best to use OneDrive.
2. Pros:
• Your files are available on all your devices
• Easy to share files with others
• Your files are backed up
Cons:
• Some files may not sync properly (can be corrected)
• Problems with file duplication (if you don't set up OneDrive correctly)
• You cannot selectively sync files in the Desktop, Documents, Pictures, Music, and Videos folders. You must sync all files or no files.
3. Yes, files sync to all your devices. To stop the sync, go to Manage Backup.
I have Microsoft 365, which offers so much more than OneDrive alone. So I would advise you to go with that.
▶️ Video: Sync OneDrive files and folders