Toll the Dead spell, Does 1d12 dmg mean they do not get a save if they are missing health?

Surprise rules, does a character even have a reaction to take before the start of their first turn? I

Are the non damaging effects from Sickening Radiance (exhaustion and no invisibility) tie to the save?

Jump to another target: what happens when someone rolls a Critical Hit on Chaos Bolt?

Xanathars says identifying a spell being cast is a reaction

The right most picture of Diagram 2.5: Cones Using Tokens in XGtE violates how cone effects are described on PH 204