This is fine if you really need it, and it might be a great sideboard option for decks that dont normally use 7-drops to help fight against slower decks, but the other 7-drops in the set are a lot stronger for ramp
Earlier this year, Wizards of the Coast treated us to a first look at the upcoming Magic: The Gathering x Marvel Spider-Man cards
Passionate Archaeologist, one of the strongest background enchantments, is a nice way to do some extra damage when playing with adventure cards, especially because the permanent side often costs more
#2 As long as the alter doesn't cover any relevant information or alter the art beyond recognition, you should be ok
Fable of the Mirror Breaker is now worth more than $20 and, given its presence in the deck that one the most recent Pro tour, it probably wont be slowing down any time soon