if the character is accepted up to the first day of the event, yes, they can start in xanadu world. anyone coming later will be on the ship. the slide only works once each way, once at the start of the event and one at the end of it.

glyphlinks between pairs where one partner is on navi and the other is in xanadu will be dead, just like if the character were dropped/swept. if your character can somehow sense a person through the walls of realities, they could technically tell they're still alive but i'd want to discuss that ahead of time.