get data from expression to script and move layers(up/down)

guys what way better used for getting data from expression variables and put them to script variables (i only know how get all expression string, but if only need date from one or two variables?)

for example

Expression part:

x=transform.position[0];

y=transform.position[1];

x=x+x;

y=y+y;

[x,y]

script part:

var expression_x_value="and here don't know what i must do to get X expression data"

var expression_y_value="and here don't know what i must do to get Y expression data"

alert(" x= "+expression_x_value+ " y= "+expression_y_value);

also i need move layer up or down i try do this with but not work

var myProj = app.project;

var myComp = myProj.activeItem;

var CurlayIndex=myComp.selectedLayers[0].index;

..........

if(myComp instanceof CompItem)

                                {

                                var importOptions = new ImportOptions("some file");

                                var importImg = myProj.importFile (importOptions);

                                var imported_file_for_move = myComp.layers.add(importImg);

                                }

                     alert(CurlayIndex); // check index of layer , to this layer index i want move my imported layer

                     alert(imported_file_for_move.name); //for get name

                     alert(imported_file_for_move.index); //for get  index

  imported_file_for_move.moveAfter(CurlayIndex);  // i think line this not work

thx