Is the Chicxulub impact regarded as the strongest explanation for the extinction of the non-avian dinosaurs?

Yes. The Chicxulub impact and its global consequences remain the strongest explanation.

Did all dinosaurs really die out?

No. The non-avian dinosaurs disappeared, but birds survived as a dinosaur lineage.

Yes. Their extinction is tied to the end of the Cretaceous, around 66 million years ago.

No. The event struck many groups and amounted to a broad planetary crisis.

No. That remains an active research topic, and several factors probably worked together.