Problem with TD script (from java to c#)

Hi guys. I'm making Tower Defence game and i stuck in scrip which i translated from java to c#. I have 3 errors and i can't solve them

1. Assets/Skrypty/InGAmeGUI.cs(64,53): error CS0266: Cannot implicitly convert type UnityEngine.Object' to UnityEngine.GameObject'. An explicit conversion exists (are you missing a cast?)

2. Assets/Skrypty/InGAmeGUI.cs(66,64): error CS1612: Cannot modify a value type return value of UnityEngine.Transform.localEulerAngles'. Consider storing the value in a temporary variable 3. Assets/Skrypty/InGAmeGUI.cs(95,25): error CS0103: The name buildPanelTweener' does not exist in the current context

   using UnityEngine; using System.Collections;

   public class InGAmeGUI : MonoBehaviour {

     //NGU items
        
        public bool buildPanelOpen = false;
        public TweenPosition BuildPanelTweener; 
        public TweenRotation BuildPanelArrowTweener;
        
        //Placement Plane Items
        public Transform placementPlanesRoot; // attach the placement plane root
        public Material hoverMat; // attach the hover material to this slot
        public LayerMask placementLayerMask; // calls up the layer mask selection
        private Material originalMat;
        private GameObject lastHitObj;
        
        //Build Selection Items
        public Color onColor;
        public Color offColor;
        public GameObject[] allStructures;
        public UISlicedSprite[] buildBtnGraphics;
        
        private int structureIndex = 0;
        
        void Start ()
        {
            //reset the structure index, refresh the GUI
            structureIndex = 0;
            UpdateGUI();
        }
        
        void Update ()
        {
            if ( buildPanelOpen )
            {
                 var ray = Camera.main.ScreenPointToRay ( Input.mousePosition );
                RaycastHit hit;
                if ( Physics.Raycast ( ray,out hit, 1000, placementLayerMask ) )
                {
                    if ( lastHitObj )
                    {
                        lastHitObj.renderer.material = originalMat;
                    }
                    lastHitObj = hit.collider.gameObject;
                    originalMat = lastHitObj.renderer.material;
                    lastHitObj.renderer.material = hoverMat; // sets the planes material to the highlighted material
                }
                else // if the raycast didn’t hit anything
                {
                    if ( lastHitObj ) // if we had previously hit something
                    {
                        lastHitObj.renderer.material = originalMat; // visually de select that object
                        lastHitObj = null; // nullify the plane selection
                    }
                }
                // drops a turrent on click
                if ( Input.GetMouseButtonDown(0) && lastHitObj ) //left mouse button was clicked and there is a last hitObject // if left mouse button (0) is clicked and we have something selected
                {
                    if(lastHitObj.tag =="PlacementPlane_Open")
                    {
                        // drop the chosen structure exactly at the tile’s position and rotation of Zero. See how the “index” comes into play here?
                        GameObject  newStructure = Instantiate( allStructures[structureIndex], lastHitObj.transform.position, Quaternion.identity );
                        // set the new structure to have a random rotation. just for looks
                        newStructure.transform.localEulerAngles.y = (Random.Range(0, 360));        //newStructure.transform.localEulerAngles.y = ( Random.Range ( 0, 360 ) );
                        // set this tile’s tag to “Taken” so we can’t double place a structure
                        lastHitObj.tag = "PlacementPlane_Taken";        
                    }
                }
            }
        }
        
        void UpdateGUI () {
        
            //Go through all structure buttons (buttons in the build panel). and set them to “off”
            foreach(UISlicedSprite theBtnGraphic in buildBtnGraphics )//in buildBtnGraphics
            {
                theBtnGraphic.color = offColor;
            }
            //set the selected build button to “on”
            buildBtnGraphics[structureIndex].color = onColor;
        }
        
        // this happens whenever the build arrow is clicked
        void ToggleBuildPanel ()
        {
            if ( buildPanelOpen ) {
                // hide all build tiles
                foreach(Transform thePlane in placementPlanesRoot) 
                {
                    thePlane.gameObject.renderer.enabled =false;
                }
                // plays the build panel tweener script backward ( false )
                buildPanelTweener.Play ( false );
                // sets the boolean to false ( closed )
                buildPanelOpen = false; 
            }
            
    
            else // the build panel was closed, so instead do this…
            {
                BuildPanelTweener.Play(true);
                BuildPanelArrowTweener.Play(true);
                foreach ( Transform thePlane in placementPlanesRoot )
                {
                    thePlane.gameObject.renderer.enabled = true;
                }
    
            }
        }
        // Called whenever a structure choice is clicked ( the button in the build panel )
        void SetBuildChoice ( GameObject btnObj )
        {
            string btnName = btnObj.name;
            if ( btnName == "Btn_Farmer")
            {
                structureIndex = 0;
            }
            else if ( btnName == "Btn_Cow" )
            {
                structureIndex = 1;
            }
            else if ( btnName == "Btn_Alien")
            {
                structureIndex = 2;
            }
            UpdateGUI ();
        }
    }