Hello,
1. Settings of the Mobile menu > Icon Zoom (Proportion) > set 1.4.
2. There is no such possibility, right now, but our team will consider your request. As a temporary solution, you can change the background color (Mobile menu settings > Off-Canvas Content > Off-Canvas Content WCAG Control (Background)).
3. You can do this via settings of Header sticky – https://prnt.sc/pewndv
Regards