Originally Posted by
chazus
Just a note/second opinion, everything Temp Name said is correct.
1) I've attempted to install Win10 from an external drive, and have had difficulties with it. It has something to do with how drives are formatted and build and how the USB exchange occurs. Flash drives/Thumb Drives/etc generally dont have that issue (some very cheap USB drives may, but they're rare.)
2) If you have your Windows 7 license key sticker, you can do a clean install and use the Win7 license to activate Win10, as long as Win7 was activated before like 2019, which it probably was. If your situation is any different (digital license, oem, pirated, etc), I'd recommend upgrading to Win10 first to lock it in, then do a clean install. Keep the Win7 license key regardless
3) Yes, however as Temp said, its best to uninstall. If you install Win10 on another drive while the Win7 drive is still active, the bootstrap remains on the WIn7 drive, which in turn means if you ever remove the Win7 drive, Win10 will fail to boot.
4) Depends on the situation. Are you going to use the WIn7 license?
Another note: If you REALLY want to use Win7 and Win10, I'd recommend installign Win10 on a separate drive with all others unplugged, add the Win7 drive, wipe it, and reinstall win7 on it, so the bootstrap remains on the Win10 drive.