Yes, you need to...
Yes, you need to...
It could fail if we cease using alphanumeric characters, yet it should still function.
It's okay to wait before turning it on. If you encounter any issues during activation, you can reach out to Microsoft support for assistance.
Are you asking about installing without a key and then activating? Or using a different key to activate? The problem is that Windows just clears your wallpaper and displays warning messages at startup, showing "Not genuine" in the desktop corner. You can use it without activation forever. Windows 7 supports installation without a key, but Windows 8 does not.