"However, UnrealScript is being removed."
I guess that isn't so much of a shock.
"Unreal Kismet is being evolved to a far more powerful system. Epic claims that you will be able to create a mod entirely using the updated visual scripting system. The next generation of Kismet now allows for scripting of object behaviors, as well as the previous functionality for levels. It includes a system for visual debugging, as well as a template system referred to as blueprint, for placing of objects with pre-defined behaviors in the world.
For those wishing to customize further, programmers can click on a property and edit the C++ code directly, with no rebuild time required."
Start with the C++ coding and learn about Kismet. Good luck!
Hope your question is answered.