I see one issue with current notyfication feature in "bell icon"
I still see ZERO as a number in this icon.
But when it is = 0 then no one number should be displayed (just clean BellIcon without number), as currently it is a little confusing.
Please follow this to Lithium
Yes. The interpretation is definitely correct. Make the element feasible only if there are elements! -> Lithium
Also for mail counter. No mail = No counter