I don't know if it was Dolphin or ???, I do have Gnome as an alternate desktop on this install and was logged on for a while with that as a desktop using the hover feature. I logged off, and back on again into the KDE desktop without a complete shutdown, but I don't know if anything used in Gnome would 'hang over' into the KDE desktop. I'd like to know more about using Nautilus but don't want to risk screwing up my system. Can someone point me to the thread concerning nautilus and KDE?
If I am reading between the lines correctly, the impression I get is that you have task-gnome installed???? If so you already have Nautilus available in KDE. I have a KDE install on a computer with task-gnome-minimal installed which provides Nautilus. I can run it with Run Command. If it works for you I guess you could make a menu entry or launcher.