Sage 300c - First Deployment

Hi,

We are in the process to migrate one of our Sage 300 2018 customers to Sage 300c but we will don in steps as they have a few third-party and add-ons that are not in same technology. So a few questions tp someone of you that already this before : 

1. If we install in same server that Sage 300 2018 is in, we just need to install web screens and that's it right ? I suppose we need to have IIS there? So from same Sage 300 2018/Update file we do Sage 300c?

2. Our customer receive a Product Activation file with Serial Nos and Activation Codes....that means its is a separate registration between Sage 300 and Sage 300c?

3. Customer it is capable of install any of those versions if needed if a user for example use a third-party or add-on that it is not still a web screen?

4. Any other requirement or something Im missing?

Thank you very much for your help