1/ Create menus via Dashboard > Appearance > Menus, then go to Theme Options > Header builder > select menus for Main menu and Mobile menu elements.
2/ Provide URL of the category page and describe the desired result in more detail. Maybe it can be achieved using custom CSS code.
3/ It is aligned center according to the parent Main menu item.
Try to activate Mega Menu Dropdown Full-Width in Theme Options > Header builder > Main menu.
4/ Could you provide URL and temporary wp-admin access?
5/ Theme options > General > Enable Old Widgets Panel > On, then go to Dashboard > Appearance > Widgets > add widgets into Shop sidebar area
