The created card doesn't necessarily need to be from your deck, library, or sideboard, and could be a card in another set or format, as if it was created "out of thin air"
Theyre effectively counter-quadruplers, because both the initial replacement effect adding counters and the death trigger are enhanced
I have yet to see someone open their fifth copy of a rare or mythic, though, so I dont know how much Vault progress those will give you
Most Pokmon cards are graded in accordance with Professional Sports Authenticator (PSA), which is scaled from a 1 for poor and a 10 for Gem Mint
Stolen by the Fae is an X spell and a bounce spell that also gives you a bunch of Faeries
It's an open-ended question, but if you can't answer it everything else in the deck won't matter