I had the same confusion, so I checked with my attorney. They said the second point does not apply to us, so I only sent I-797 approval notice and my passport was stamped. However, it doesn't hurt if you add offer letter if you already have it.
Is this your first H1b? Do you have a PR card? Mine is almost same timeline as yours. Package delivered on 06-Sep, Status changed to 'Application Received' on 11-sep. No change after that. Don't know what that means.
H1B Dropbox Toronto Consulate
Sept 5 : Docs sent via Canada Post.
Sept 6 : Docs reached consulate.
Sept 11 : DS-160 status changed to 'Application Received'.
No update since then. Any idea how long will it take to see an update? I have an International travel planned in Oct!