SC 4? What's that? KDE ship a large number of applications in core packages. They are known as the Software Compilation. For convenience, we shorten it to SC 4.
At first sight it looks as though a number of features that were valued in KDE3 are missing in KDE SC 4. In fact most of those features are available, but may well be approached differently. Imagine a 'Road Closed' sign - you simply choose an alternative route. This is what has happened to several things, for a variety of reasons.
A particular case is of 'missing features' from kcontrol to systemsettings. Some of the kcontrol settings related to specific applications. Those settings have therefore been moved to the application, rather than being in a general control panel.
kcontrol no longer exists. Systemsettings, which has the crossed tools icon, replaces it. By default it uses an icon view, arranged in groups. You may prefer to use the Configuration option (see the spanner/wrench icon) to change it to Classic Tree View.
In KDE 3 you could choose to have usb devices mounted automatically upon plugin. In KDE SC 4 this is not the norm. You mount manually, either from the device notifier, by choosing an action, or by clicking on the device icon in Dolphin. From KDE SC 4.2 it has been possible to use an alternative device notifier plasmoid that does support automount functionality. You can read about it here
Advanced users may prefer to study the creation of usb device rules. Documentation can be found in the writing udev rules guide.
To achieve this click on the plasma configurations icon (yellow curvy thing at the right hand side of the panel) and select 'configure panel'. Then under 'more options' enable autohide. Manual hiding, as in KDE3, is currently not possible.
In KDE SC 4 you have to bring up panel control (use the plasma icon, the yellow curvy thing at the right hand end of the panel). If you lock your widgets (or your distro does by default) you will first need to unlock widgets. This can be done from the right-click menu on the desktop. When your cursor moves over a widget (or plasmoid) it changes to a diamond shape. Use that cursor to drag each widget to its new place.
Finish by clicking on the X in a red circle on the configuration panel, and lock your plasmoids again if you wish, (right click menu, as before).
KDE3 used to let you configure whether you wanted to see the application name (e.g. amarok) or the description (e.g. media player). KDE SC 4 always shows only the description and this makes it very hard to find applications.
If you use 'Kickoff Menu Style', you can easily find an application by typing the first few letters of its name in the 'Search' line of the 'Application Launcher'. Once you have found it you can choose to add it to Favorites or to add a launcher icon into the panel or on the desktop.
If you dislike the 'click on everything' style of Kickoff you may like to try Lancelot which has most of the advantages of Kickoff and some nice tricks of its own.
If you prefer the old K menu, then right click the K menu icon and choose "Switch to Classic Menu Style". Now you can configure how to show applications in the menu: Right click on the K icon -> Application Launcher settings. Check the "Show applications by name" option, click OK. Done.
Kbluetooth is in active development. Version 0.4 is due for release very soon.