In July, PSA had their bulk tcg pricing available for Oversized cards which I think may have been a mistake, but it was honored by PSA
As is generally the case, both cards have the exact same set of abilities and power, but the application of artwork, holographic material, and textured gloss is completely different
I might switch him to 5/6 because he feels like he wants to be a finisher in a control deck, and they like having that bit more toughness than power
If another effect modifies how much damage your source would deal, including preventing some of it, the player being dealt damage or the controller of the permanent being dealt damage chooses an order in which to apply those effects
Do some research online, chat with friends about card synergy, and follow along with pro and semi-pro YouTube and Twitch folks for the especially expert-tier fare
Since your opponents draw seven cards at the start of the game, that leaves you with only nine more cards you need to mill