Nixos, как я могу искать пакеты на определенном канале?

Нет, вам не нужно покупать лицензию MS Windows.

Да, Wine может имитировать разные версии Windows.

Из Руководство пользователя Wine:

Wine has the ability to mimic the behavior of different versions of Windows. In general, the biggest difference is whether Wine behaves as a Win9x version or an NT version. Some applications require a specific behavior in order to function and changing this setting may cause a buggy app to work. Wine default Windows version is Windows XP. Some applications may perform better if you choose Windows 98.