For the quantity selectors, you will notice that the CSS from the YITH plugin is also setting this to not display. To make this display you just need to add form.cart .quantity to the previous code, like so:
form.cart .quantity,
form.cart button.single_add_to_cart_button {
display: block !important;
}Regarding the other issues, it may be that the YITH Catalog plugin is disabling the cart functionality, to ensure it really is catalog mode only. You would need to ask the plugin support for help with this, as it is outside the scope of the theme.
Also with with regard to changing the button text, if that plugin has options to change this, then this is also outside the scope of the theme, and I would recommend you consult the plugin’s documentation or ask their support for help.