These days most PCs can boot from USB, so you need no DVD drive any more to install Windows 10. Installing Windows 10 from a USB flash drive is much faster than optical drive setup. Modern devices support both BIOS or UEFI firmware modes. However, it can be useful to create a bootable USB driver which works in native UEFI mode.
In Windows 10, Microsoft Account is the default way of signing in. This means that the OS requires your Outlook.com, Hotmail, MSN, or Live ID email address and password to sign-in to Windows. It is still possible to sign in using a local account that does not involve internet-based credentials, but the option to do so is hidden behind various buttons.