First, WotC could tweak how the bonus sheet is implemented on MTGA: They have done it in the past, although it really seems extremely unlikely to happen here
I dont see any on eBay, but I suspect Magic cards signed by famous people who play the game could be noteworthy
A card with only these minor defects can still be classified as Near Mint (NM) , provided it is in perfect condition in all other aspects (no scratches, bends, wear marks, etc.)
This applies to every other Vampire you play after Vampire Socialite, providing your opponent has lost life in the current turn
That is, if Gigantoplasm is a copy of a creature with base power and toughness 2/2 and you activate its ability making it a 4/4 creature, another creature that becomes a copy of Gigantoplasm will have base power and toughness 2/2