There are no death saves in D&D5. Thats an AD&D thing.

You get saves during negotiating if you will die, but those are IIRC Constitution ? Cleric doesnt get Consitution Save Proficiency. They get Wisdom and Charisma.

Cleric is an awesome class, probably the strongest single class in the game, and unless you pick Trickery, you only get good to overpowered options (Light).

Skeletons are ranged in BG3 and are thus massively prefered over Zombies.