Do I have to keep the installer (104 MB), even though WD SmartWare 2.4.11.4 (66.8 MB) is already installed?
No, you don't have to keep the installer, because it won't affect the functionality, but keeping it can help in case something goes wrong with the official installation. However, you can always download the application again if you need it installed.
Download page: http://www.wdc.com/en/products/products.aspx?id=940
