One important identifying factor when looking for Shadowless cards is that they are guaranteed to come from English long crimp booster packs and have a chance appearing in short crimp packs
They are the rarest Magic cards since they are printed in limited numbers, typically just 50 per type (regular/foil/etched/etc.) per set the card art is printed in, and only given to the artist
ScreenRant: From an artistic perspective, do you prefer decks that are themed (such as a Puppy deck, or Winnie the Pooh Pirate deck), or do you prefer to look at the card mechanics
#2 As long as the alter doesn't cover any relevant information or alter the art beyond recognition, you should be ok
I'm honestly not sure if a pirate deck will work or not
By flattening these before submission, you can improve your chances of jumping a grade