Updating Number and Apple ID

Your phone number is not connected to your Apple ID. As for the answers to your questions:

1. Updating your Apple ID does not give everyone in your Contacts your new phone number, you will need to let them know.
2. Others will not automatically get your new phone number. Note that some services like Messages can be used with your Apple ID and not your phone number, so they may still be able to use those services to contact you if your device is set to receive those communications from your Apple ID. For Messages this can be checked at Settings > Messages > Accounts. You will see an option there to receive from phone number, your Apple ID, or both if checked.

just my updating your number in Apple ID won’t share your number to anyone by Apple. You’ve to explicitly share your number to connect.