Not a specific one as far as I know. The Zorin developers said they'll release it during Summer. So it's in the very near future.
I believe you are not restricted and you can install it on as many 'Personal' computers as you want. There is no DRM but ethically, for enterprise usage, you should look at their business licensees.
I believe you'll get a permanent download link to the .iso file emailed to you. There are not accounts system.
Zorin 16 is based on Ubuntu 20.04 LTS. So the OS is going to get supported for a good amount of time ... at least for 2-3 years (I might be wrong. It would be nice if someone could provide more information on this). But for more information on end of life support plans on Ubuntu take a look at here:
Yes, you can change almost everything on Zorin OS. You can use a different shell, use different Icons, use different themes, ... basically anything. Zorin OS is extremely customizable... unlike Elementary OS.