You also can create a bootable Flash drive with the Media Creation Tool (that's how I do it). If your computer can boot from USB, I think that is the way to go. Flash drive has also the advantage, that current updates can be stored on it as well. That is the beauty of Windows 10, only max. 3 Updates need to be stored and the system is up-to-date in no time (unlike Windows 7 with over 250+ Updates to download).
A 8GB drive is sufficient unless you want to do an All-In-One (containing home/pro and 32/64bit),then you need a 16GB drive (which has room to spare for the updates)