Whether a parent-sponsorship application can proceed without an in-person appearance, using a proxy (mother or spouse)

I’m a citizen and would like to sponsor one of my parents for a green card.

I have the following questions:

1. Can this proceed without an in-person appearance, using a proxy (mother or husband)?

2. If processed within the U.S., does my mother need to continuously meet the residency requirement (can she return to Korea and wait for the visa there)?

Thank you.