You can choose to resign whenever you want
opponent abandoning game in my turn

Opponent got off to a bad start, losing took and 2 pawns early. He abandoned the game when it was my turn. How is this possible as I thought abandonment was related to a player taking too long to make their move?
If the game isn't in your Archive, the the live server restarted, which aborts all ongoing games. If it says abandoned, then you won by abandonment, which isn't any different than winning by checkmate or resignation from a rating standpoint. It just means your opponent either left the game or was disconnected for too long.
Aborting the game isn't possible by the players once moves have been played.
Opponent got off to a bad start, losing took and 2 pawns early. He abandoned the game when it was my turn. How is this possible as I thought abandonment was related to a player taking too long to make their move?