Shopify - Add product to cart automatically

shopify-add-to-cart

  if (typeof Shopify === 'undefined') var Shopify = {};
  Shopify.cart = {{ cart | json }};
  Shopify.toAdd = 378589397;
  var surchargeInCart = false;
  var total = 2507; // total in cents.
  for (var i=0; i<Shopify.cart.items.length; i++) {
    if (Shopify.cart.items[i].id === Shopify.toAdd) {
      surchargeInCart = true;
      total -= Shopify.cart.items[i].line_price;
    }
  }
  if (!surchargeInCart && total < 5000 && total >= 0) {
    var params = {
      type: 'POST',
      url: '/cart/add.js',
      data: 'quantity=1&id=' + Shopify.toAdd,
      dataType: 'json',
      success: function(line_item) { 
        window.location.href = '/cart';
      }
    };
    jQuery.ajax(params);
  }
  if (surchargeInCart && total >= 5000 || surchargeInCart && total === 0) {
    window.location.href = '/cart/change?id=378589397&quantity=0';    
  }
    
  // Hiding the gift-wrap quantity box and remove button.
  jQuery(function() {      
    jQuery('#updates_' + Shopify.toAdd).hide().parents('li,tr').find('a:last').hide();  
  })
  
  

Anyway to adjust the code above to automatically add a "processing and handling" fee of $19.95 to the cart when they add a product?
(optional)And maybe also have a small image thumb to represent what the fee covers there as well?

Thanks for any help!