the larger the original imperfection and thus the inked area, the greater the reduction of the cards value
For set-level detail on M6, see our Storm Emeralda pull rates and best cards guide
Personally Id focus on sealed pre-release kits as the long term value item the Charizard promo alone will push the value of those up but a well graded set of Amazing Rares will be a fantastic mini set of cards to focus on in its own right
Flickerwisp can target any permanent, so you can even get rid of your opponents tokens or target a land for it to come back untapped during your end step
Technically, these are creatures already, but they wont be treated as such until you reach the devotion threshold required for them to count as creatures
Every Vintage deck would play at least a few Mox artifacts, depending on the colors of that particular deck