Ad geschutzte merker; In Codesys You can select any variable to be retainable.
How to start: I downloaded the manual from 3s-software and used some evenings on it, with a marking pen and some post-it pads. You will also find example programs in the download area.
Aanalog scaling: There are several Codesys libraries out there, Wago has probably many different also. It's also worth while to take a look at the library from www.oscat.de.
Tip: Look into the user forum http://forum.3s-software.com/