How darkvision interacts with creatures that exploit dim light/darkness, can it still Hide/turn invisible?

There is no surprise round in D&D

Could I use the action from spell Dragon’s Breath in all following rounds I casted it while within duration and concentration?

Would an Artificer’s steel defender stop working if it stepped in antimagic field?

How would you rule it? PC puts NPC into death saves with Sword of Wounding. At the start of NPC turn, 2 things happen:

Does Chill Touch prevent a creature from gaining temporary hit points?

If a D&D rule modifies another rule, it modifies only what it says it modifies

Can psionics be affected by anti-magic. Like the anti-magic cone from a Beholder?