To answer my question #2 (based on fluteflute's helpful demonstration) the notification consists of an update in the "StackExchange" icon/menu in the top left of the page.

To answer my question #2 (based on fluteflute's helpful demonstration) the notification consists of an update in the "StackExchange" icon/menu in the top left of the page.

To answer my question #2, it would appear from DanM's answer that the notification consists of the @ icon in the top of the page turning red.

To answer my question #2 (based on fluteflute's helpful demonstration) the notification consists of an update in the "StackExchange" icon/menu in the top left of the page.