First when I decided to install kubuntu-desktop on the same machine as my standard ubuntu-desktop, I tried to integrate those two in a way that I use some of the same applications on either desktop. I failed doing that because of integration issues (I'm not talking about the look!).

Now I like to try a different approach: I want to separate those two to the max.
But I find that either desktop seems to load a lot of programs that have no place nor function in the other one. E.g. Tracker starts alongside with the Strig/nepomuk stuff, Dropbox seems to load half of gnome into KDE and kwallet starts in gnome even when no application tries to access it. Gnome keyring on the other side starts with KDE for a good reason, but I can't set it up to use my login password as authentication without entering it again to start the keyring.

What are the right settings to separate the two desktops to the maximum possible extent?
Where are the files controlling this?
For example I tried to use LightDM to have no gdm or kdm running but it seems to mess up some things like keyboard bindings ...

Is there a tutorial out there that I couldn't find while googling?
Any comprehensive information should help!