There are two ways to do this:
a. Log into your MyNCBI account with ORCID. If you're new to MyNCBI, you can create your account this way. If you already have an MyNCBI account, you can log in with ORCID and select the option to link to your existing account.
b. Log into your MyNCBI account like normal and go to MyNCBI Dashboard. Click your username in the upper right corner. This will take you to your account settings. Under Linked Accounts, click "Change" and search for ORCID.
If your journal/publisher is integrated with ORCID, and you submit your ORCID ID with your manuscript submission, then yes. However, other works will not automatically be added to your record.
Yes. They will need to create their own ORCID account, and you will then be able to add them as a trusted individual. For information on how to add trusted individuals, see this video tutorial from ORCID.
Visit the ORCID Help Center for a comprehensive knowledge base and to submit a support ticket. You can also ask a UofL librarian for help with basic ORCID questions.