ungraping to parallel 12 from 8

I need to upgrade because from what i read parallels 8 doesn't work with the newest mac ox. if i upgrade to 12 to i need to reinstall windows and will 12 work with windows 7??

 

If you have working condition Windows virtual machine that will be stored in your Mac as .pvm.
No need to reinstall Windows virtual machine.
Upgrade to Parallels Desktop 12 is possible for an existing Parallels Desktop 10/11 or has to purchase a full version.