- KDE stands for the K Desktop Environment. It is a GUI,
meaning a layer that provides a sustainable look and feel at the
linux desktop.
- If you would like to work with Servers, I recommend picking an LTS
(Long Term Support) version of Ubuntu. As is now, Version 10.04 and
Version 12.04 seem to be a fine choice. If you would like to write
an application, you need to learn how to program, something which is
out of the scope of this question.
- Yes it is, and you could be able to see it if you connect via
ssh to your server with the following flag:
ssh -X user@domain <port>
NOTE: Wikipedia in particular notes about the name:
The K was originally suggested to stand for "Kool", but it was quickly
decided that the K should stand for nothing in particular. The KDE
initialism is therefore expanded to "K Desktop Environment".