Hello,
1) All the CSS improvements were made in Theme Options > Custom CSS > global custom CSS + Theme Options > Typography. You can expost options from the staging site (Theme Options > Import/Export > http://prntscr.com/miedx1 ) and import to production site after update (Theme Options > Import/Export > http://prntscr.com/mieedf )
2) It just widgets are messed up on your staging site and it’s not because of the update but because of the creation of staging site. All you need is just make sure that all the widgets are in the correct widget areas (Appearance > Widgets)
3) This is the element of one of your plugin, filter plugin I suppose https://codecanyon.net/item/woof-woocommerce-products-filter/11498469 . Check the plugin settings or contact plugin author and ask if you can disable this filter.
Regards