While Oko has synergy with the deck, both in terms of having a lot of low-impact cards to upgrade to 3/3s and creating artifacts that become Mox Sapphire when Urzas on the battlefield, Urza strategies are extremely high-synergy and generally not looking to attack with 3/3s as a meaningful part of their gameplan
If you cant, you always have the buyout of trading this off in combat or waiting for chapter three to draw some cards
The opposite is also true: if you aren't black at all, then you know you aren't going to play the Extraction and, no matter how strong it is, it's not really something to consider for your deck any longer
When an ability affects more than one player, the players take it in turns to trigger its effects, starting with the current player and proceeding clockwise (so the person to your left goes after you)
Yes, it's a pretty pricey instant, but you can cast the card for free if your opponent searches their library this turn