Found a web site (linuxquestions.org) that gives a possible solution to the single-click problem - "possible" because I probably need to reboot before it works. Found via search on ixquick for:
linux kde "single click" -install
Apparently there is no way to change the click method via a "control panel" option unless you have KDE fully installed; simply installing a few apps without KDE fails to install a full KDE control panel.
To modify to Single-Click open the file ~/.kde/share/config/kdeglobals and add the two lines:
The SingleClick line MUST be entered in the [KDE] section: if this already exists add SingleClick in that section, otherwise create it as above.
Still cannot find out how to view hidden and network folders in the app file selectors.