Optimize Collection Page for Browsing & CRO

Adjust my collection page using settings my theme already has (check theme settings before building anything custom):


  Show [3/4] products per row on desktop, [2] on mobile
  Show sale prices with original price crossed out
  Add product badges for “Sale”, “New”, “Best Seller”
  Show total product count at the top


Apply whichever of these exist as native theme settings. Quick-add AJAX buttons and infinite-scroll pagination are custom functionality — tell me if my theme doesn’t support them natively rather than building custom code for them.