If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Tough Cookie (an Artifact Creature — Food Golem) to activate Maraleaf Rider's ability (an ability with "Sacrifice a Food" in its cost).

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.