Henry,
Here is an online reference you might find useful.
pmstudycircle.com/2016/03/what-is-a-project-kick-off-meeting/
In practice, the kick off meeting is usually held once the planning is complete and the project is ready to be executed. At least, that is based on my practical experience although some project work is sometimes underway by that point.
Regarding #2, in my experience, I would not hold a kick-off meeting unless the key stakeholders and team members are present, either physically or virtually. It is a key point in the project where you have the opportunity to get everyone together to discuss the various aspects of the project and can really help set the tone for the project and its success. I would reschedule the kick-off meeting.
Hope this helps.
Mark