Yes, you can install Windows from a USB drive and use the activation code from the DVD.
Yes, you can install Windows from a USB drive and use the activation code from the DVD.
I believe so. I’m not aware of any keys that pay little attention to the installation media you choose. I assume the products you’re looking at are retail keys, which means you won’t face OEM restrictions. You could even create your own USB drive and install it using the Windows Media Creation Tool, ensuring it runs with the latest Windows 10—though the DVD version is probably outdated. What matters most is the key itself.
They haven’t done it before. I don’t recall any DVD copies of the Win10 installer being available; only USB drives were offered.