Digital render, not actual card
Black for Common, Silver for Uncommon, Gold for Rare, and Red-Orange for Mythic Rare
Cards known as the flip cards from the Kamigawa set were so hard to understand in a first glance, that they would never be used again
Since nearly every character card interacts with Puppy cards, bringing a ton of them ends up being really strong, as you will get value out of everything in your deck nearly anytime you use a card
If you have very expensive vintage Magic cards, I would definitely look into the larger auction houses as they have the unique advantage of getting you you national attention
I like the caveats in card games (phrases like "but the value of X is up to the number of..."), so I'd be happy if they were still being used, haha