Hi thanks for the interest in the Events Calendar Pro. I can help you out here.
See my answers below:
a) Speakers should be handled ~like categories in WP. So there should be a global list and one should be able to add X speakers.
The Additional Fields in Pro are not able to do that, but you could add in your own custom taxonomy for that.
b) Another requirement is adding a link to each speaker, so the rendered name can point to a page which provides additional information about the person.
Again that could be possible, but only through customization of above custom taxonomy.
AS for customizations we can help answer some questions, but for the most part they are beyond the support we can provide.
Let me know if you have any follow up questions.
Thanks