How to set up Repetier Host and Sli3er for first use on Kossel (or many other 3d printers)

Great guide by electronhacks where he explains how to setup Repetier-Host and Slic3r for first print on Kossel 3d printer. It deals with many uncertainties that beginners have when setting up the machine first time. It is great learning resource for other similar 3d printer setups.