Yes, that's accepted as well. "Alle og enhver" is used for emphasis.

They are in some cases, but "enhver" is seldom used as a subject on its own - it's usually modifying a noun or used as part of this expression when it's occupying the subject spot.

As a standalone subject, it's safest to default to "alle", while using "alle og enhver" for emphasis.

"All and sundry" means "everyone".

This would mean anyone rather than everyone

To me, "Hver liker iskrem," sounds like, "Each [one/person] likes ice cream."

Alle og enhver is akin to English expression, "Everyone and anyone," or "Everyone and their dog."