No, you cannot use a Win7 code to activate Windows 10. Each operating system requires its own activation method.
No, you cannot use a Win7 code to activate Windows 10. Each operating system requires its own activation method.
Only when you switched from Windows 7 to Windows 10 during the free upgrade window. You’re able to start from the external USB drive, or if you’re targeting Windows 10, simply get the installer creator and run it on a USB drive.
You can't use Win 7 code with Windows 10, otherwise you'll have to pay for it. If you're unsure about installing Win 7 and then getting it upgraded to Windows 10 for free, there might be issues.