Live Event Registrations & Speakers

Hi all, 

I have to organize a webinar with Teams Live about once per month and I had a few questions that I couldn't find the answer to on the support website. Maybe you can help me here? 

1. What is the maximum number of speakers that I can invite to my live event?

2. If I have to make changes to my webinar (e.g. add a speaker) will the registrations' link change for the attendees? I'm worried that I'll have to notify all registrants to that point if I make a few changes to the event. Which changes would cause the Link to change? 

I literally could not find an answer to these questions and I'm relatively new to this. Can someone help me out, please?