When Cauldron Familiar enters the battlefield, each opponent loses 1 life and you gain 1 life.
Sacrifice a Food: Return Cauldron Familiar from your graveyard to the battlefield.
You can’t activate Cauldron Familiar’s last ability unless it’s in your graveyard.
In a Two-Headed Giant game, Cauldron Familiar’s first ability causes the opposing team to lose 1 life twice, and you gain 1 life once.
If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Gingerbrute to activate the last ability of Tempting Witch.