Preferably some sort of dropdown menu, and if that's not possible anything that will make it possible to start a certain part of my script and when it's done, return to the initial position to make another choice..
I don’t think you can currently create additional menus in Photoshop (unless you have the source code and can program C++ or some such).
But I might be wrong …
But you can create dialogs (see »User-Interface Tools« in »JavaScript Tools Guide CS6.pdf«) or Panels (the easiest Option for this would be using Configurator to create a Panel that triggers Scripts).