Hi,
Regarding your issues add the code below to your custom css option.
1)
.woocommerce .quantity .minus, .woocommerce .quantity input.qty, .woocommerce .quantity .plus {
position: relative;
height: 30px!important;
}
2)
.single-product button.single_add_to_cart_button.button.alt:hover {
color: #fff!important;
}
3) I can’t find the 1st checkbox of your screenshot but use the code below to adjust the font family and size of the 2nd checkbox in your attachment.
.woocommerce .checkout #ship-to-different-address label {
font-size: 1em!important;
font-family: Helvetica, Arial, Helvetica, Tahoma, sans-serif!important;
}
4)
.page-id-9996 .woocommerce-checkout-payment{
display:none;
}
-Rui