I would say #2 since Dedaria is very squishy, so the Earth Main being in front of him to tank will help his survivability a lot.

The first 1 is better especially if you have higher initiative. Deidara being in position 1 can lessen the chance of him being interrupted by the opponent's pos 1 ninja with a mystery when he is doing a mystery, and Earth Main can stack stack shields on him. But anyway, Deidara is strong even with less initiative than the enemy.

depends on your common enemies. both work fine.

I'd say the first option as most people don't have their ninjas in that bottom row, and obv you can destroy in round 2 with the mystery.