Using A Friends Unused Product Key & Driver Question

Hello
I am currently running Windows Vista on my computer, but would like to upgrade to Windows 10. I have a few questions.

1. My friend, who has a Windows 7-running computer, is willing to give me their product activation key for their free Windows 10 upgrade. Would it be possible for me to download the Windows 10 ISO file, then use my friends product activation key when it asks for one?
2. I know that I will lose my files and programs if I do not back them up to a USB or external hard drive before installing Windows 10, but will Windows 10 also wipe the drivers I have installed on my computer? (Such as my graphics card driver, sound drivers, printer drivers, etc.)

Thank you!

1) I think you can clean install Windows 7 then activate with your friend product key but it is illegal. Then you can upgrade by extracting ISO and just click setup.exe
2) you will lose file in C if you clean install windows 10( by burning ISO to USB) but if you upgrade like above, you will keep your file. I don't know about driver, but Windows 10 work well with wifi, Bluetooth, Ethernet, sound..