You can actually change icons in your app drawer with Nova (or at least Nova Prime - so long since I used free Nova that I can't remember). Just long press on the icon, select edit, choose an icon. In fact if you change the icon in the app drawer it also changes it everywhere else.
I've never had a problem with creating folders, but I prefer to create them in Nova's app drawer settings because that creates folders where I can give the folder a custom icon, nest folders inside folders, place them in the dock, and keep them in an app drawer tab. Very, very much more flexible than the ad hoc "drag a couple of icons on top of each other to make a folder" approach that most launchers provide (including Nova).