URGENT help request for meeting today with 100 attendees - several questions

Hi - I am hosting a meeting today with 100 attendees.

1. Registration was required and attendees received the confirmation email.  Do they also automatically receive a reminder?  Or will they get any type of notification?

2.  I want to resend the confirmation email to everyone (because I am not sure if they receive a reminder).  I open the list of registrants >> select all >> see the button to "Resend Confirmation Email".  Does this select ALL 100 registrants across the 8 pages, OR just the ones on the 14/100 on the first page of the list?  Do I need to select all registrants on EACH page and click the Resend button?

One of the attendees will be co-presenting with me and sharing her screen.  This is my plan.  Is this process the way to go?  I start the meeting early > my-co presenter joins early  >> She unmutes and turns on video  >> I give her access to share her screen >> admit all registrants into the room >> I introduce here and she presents.   Will this work?

Thank you for your help!