Hi! Answers below:
Since Prodigy is a developer tool, the seats included with the company pack are developer seats. So everyone who has access to the Prodigy Python library, back-end, database and CLI and can start annotation tasks requires a seat. Annotators who only have access to the web app don't need a seat.
So with a company pack, you can have up to 5 rotating people work with Prodigy and start/stop annotation tasks or run experiments, and an unlimited number of annotators who only access the app in their browser and do the annotation.
Prodigy doesn't ever connect to our servers, so you don't have to input the license keys in order to start the software. However, you should keep a list or spreadsheet of who is currently using the software and who the licenses are allocated to.
Yes, that should be no problem. Licenses are "floating" and can be transferred within your team. So if a person is working with you in some capacity, you can allocate a seat to them.