Yes, just edit, save, and run. Since you are editing the part where the script describes its parameters to Gimp, you may have to restart GImp to see that chnage take effect (of other code changes, you just save an Gimp will run the new version. Edit with caution, Python is sensitive to line indentation, and some editors like to replace spaces by tabs and this messes u the code. So use a real code editor (Notepad++, UltraEdit,...), and not the Microsoft ones (Notepad, Wordpad...).
To move a layer in the script that would be layer.set_offsets(x,y) (if this is the only layer: image.layers[0].set_offsets(x,y), whee x and y are the new coordinates of the top left corner of the layer.
To move a layer in the script that would be layer.set_offsets(x,y) (if this is the only layer: image.layers[0].set_offsets(x,y), whee x and y are the new coordinates of the top left corner of the layer.