Magento 2 – Cannot Read Contents from File: file_get_contents Warning

You can create observer for events checkout_cart_product_add_after and checkout_cart_product_update_after and in your observer you can check cart total and add or remove product from cart dynamically.
You can try below codes :
getting totals

$totals = Mage::getSingleton(‘checkout/session’)->getQuote()->getTotals();//Total object     
$subtotal = round($totals["subtotal"]->getValue());//Subtotal value 
$grandtotal = round($totals["grand_total"]->getValue()); //Grandtotal value

adding product to cart

$cart = Mage::getModel('checkout/cart');
$cart->init();
$cart->addProduct($my_product, array('qty' => $qty_value));
$cart->save(); 
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);

Similarly you can write for removing product from cart if while updating cart order total goes down the required amount.
Also in you can do necessary changes in item.phtml to remove remove link, qty update box and other stuff that you don't need.

You can check in Category page by using below code.

$_category  = $block->getCurrentCategory(); // get Current Category
$_imgUrl = $_category->getImageUrl()

If $_ImgUrl is not equal to blank means category has image else not.

Thanks