I haven't used kde in a while, but I'm pretty sure you can poke around the system menus & configure desktop, and you'll strike gold.

As far as the image in your monitor centering, sounds like a config issue. In the past, I've found that I have to run the reconfig a lot of times to get it right - especially with an LCD.

All supposedly can be configured within KDE, but I'm a like using dpkg-reconfigure - again - personal preference.