Can I do a fresh install of windows to a usb from the CD?

won't work.  your computer and Microsoft will not allow an o/s to be installed on a removable drive.  Really, there's little reason to do so -- Win 10 allows you to make a thumb drive or DVD that will boot and repair the Windows system if it goes down.  This blank thumb drive costs about 5 bucks at WalMart [16 Gb minimum size and get the name brand].  The CDs/DVDs supplied by Microsoft can be used to install on a new computer without a DVD drive if you use an external reader and set the BIOS/UEFI to boot from USB.  [Yup. they're pretty restrictive about trying to install same licensed copy on more than one computer ... and there are other features designed to prevent this that I haven't mentioned.] -- grampa

No. 

What you can do is use Microsoft Media Creation Tool (website) and download the tool.

Running the Tool will download the latest version of Windows 10 and place it on a USB Stick (bootable install files) so you can then Install Windows 10 on a computers hard drive.