No, KDE does not have their own virtualization gui. Boxes can still be used on KDE as well though. If you really want nothing to do with Gnome, then virt-manager will be your best option.
Gnome 3 under the hood but it is nothing like the Gnome 3 your thinking about. It is more like Gnome 2 as far as the UI.
There is still a Gnome 2 fork around also. Cannot remember the name. Used that in the early days but had some minor but annoying compatibility issues with some apps so went to Cinnamon which is based on the modern base to avoid those.