The first thing I like to install is the KDE Network management widget. It is not present in Debian KDE by default.

package: plasma-widget-networkmanagement

 

Another thing noticed is the odd message “Networking interface unmanaged” instead of setting and displaying a name

Fix:

sudo kate /etc/NetworkManager/NetworkManager.conf

The file probably contains:

[ifupdown]
managed=false[/code]
Change false to true and restart Network Management
/etc/init.d/network-manager restart[/code]
.
12 hour time:
Open KDE Country. region, Language applet:

Times & Dates>Time format>

Change to pH:MM:SS AMPM

 
Other widgets to add:
System tray (Contains volume, USB notifier etc)

Task manager (this is the horizontal tab of apps)

 
Favorite apps:
Shutter (screenshot manager)

Gimp (Image manipulator)

mc (file manager)

filezilla (ftp client)

gparted and parted

emacs

You can install all these at a go:
sudo apt-get install shutter mc filezilla gimp libx11-dev libxtst-dev emacs
libx11-dev and libxtst-dev are the dependencies of ksuperkey (along with make and build-essential).
Video thumbnails in Dolphin:
Install mplayerthumbs.
sudo apt-get install mplayerthumbs
Now enable previews in Dolphin settings>General>Previews>Video files(mplayerthumbs)
Addon scripts
Ksuperkey (Allows mapping of Win (superkey) key to the KDE app launcher, and simultaneously use  shortcuts with the key too. Follow these instructions.