Use established auction houses like Goldin, Heritage Auctions or PWCC, which have authentication processes and serious buyer pools
But is grading worth it for you
If more than three other nontoken permanents you control leave the battlefield simultaneously, that choice is made only for the first three
They have power and toughness printed in the bottom right corner, but those stats do not matter until the vehicle is crewed
Example: Diseased Vermin reads, in part, "At the beginning of your upkeep, Diseased Vermin deals X damage to target opponent previously dealt damage by it, where X is the number of infection counters on it." If Diseased Vermin phases out, it "remembers" how many counters it has and also which opponents it has previously damaged
Should the card successfully flip at least once before landing on the table, then any tokens the Chaos Orb touches are destroyed including the Chaos Orb itself