I am not sure what's it that you want in your question, because it's been a while since I used KDE or Kubuntu. Do you want to know/change the default settings that come installed with KDE installation?
They will be present in default settings directories of KDE package. Now, you can read these links below to get an idea of how KDE settings are stored, if that's what you wanted.
In the above link, you can read the Directory Tree section to know where the settings are stored for various config files, including wallpapers you want.
These are links to some places where people tweaked with the config files a little:
If you wanted to just change the settings, you might have heard about systemsettings-kde4 package before... I think it comes with KDE.
Probably, this post will help you in configuring the config files a little more:
I think the settings you are asking for can be found somewhere in the kde filesystem as mentioned in first link.
Excuse me if I have mis-interpreted your question. Hope that helps!