Apple Watch screen cracked Will it be waterproof after screen replacement?

Apple doesn't repair their Watch screens, instead you'll get a full replacement which will be water resistant. If you do a repair thru a 3rd party and they just replace the screen it will no longer be water resistant.

Unlikely.

Apple watches aren't waterproof, at best they are water resistant , and judging from questions to this group the water resistance varies depending on what you are doing and the age of the watch.