doubts about webinar

[Bikatelier]

Hello everyone, tomorrow we need to have a large meeting with approximately 500 attendees with two hosts and a special guest in which the attendees will ask questions to the guest and will be moderated by the hosts.
According to what I have read in the zoom manuals, the best option is to hold a webinar.
I have some doubts, such as whether I will be able to give access to the 500 people who may sign up and, above all, whether I will be able to selectively give microphones to those who are convenient for us during the webinar.
Due to the nature of the webinar, it is essential that guests can speak with our special guest.
Thank you very much for your help.