Should entire card be clickable?
A whole card CTA is useful as it is a large tap area, but other than that it introduces a lot of accessibility issues and I would encourage you to avoid it in most circumstances. If you make your whole card clickable (i.e. a hyperlink) then all of its content becomes the link text.
What is a product card?
A product card is a specific page with all the detailed information about your product. The better customers understand your product`s characteristics, the more opened they are to purchasing it. Accordingly, an empty or poorly compiled product card can neither catch customer's attention nor earn their trust.
How many buttons does a page have UX?
Don't have more than one primary action button on the screen at a time. Let users focus on the task at hand. You can have more actions on the page, but make sure there is only one primary. Users have expectations of what a single button on a page will do, based on the page they are on.