Yes I believe pcpp lists some USB versions for sale or you can download windows 10 off microsofts website and put it on a USB yourself but you'd still have to buy a key.

You can also download latest build from microsoft (highly recommended to get latest build available)

https://www.microsoft.com/en-us/software-download/windows10

download tool now

You will need a usb drive to burn windows.

Just use your activation key...

Depends on which particular one you purchase, but there are definitely USB versions out there. You can purchase retail Windows licenses on a USB stick and you can also purchase a key from the online Microsoft Store and load it on a USB stick.