I'm not sure if I understand you right but I think that you can define a region behind the desk and then use the StickToRegion method of the 3D actor to force the actor to stay in that region.
Thanks for answering 2.0, you're right a 350x225 image will be converted to 512x256 not to 512x512. So, there's no performance gain in saving the image in 512x256?
I'm wondering if there's any difference (performance speaking) maintaining the width and size of an image in powers of two if the video card need them that way. For example, is there any improvement in performance saving images 512x512 size instead 350x225?
I don't know if I've understood you well but if you want to teleport your actor, you can use the ChangeScene method to do it. You can use the HasItem method to check if the item is either in the general inventory for the game or the particular one for your actor (as you have implemented it in your game) if so, then you invoke the ChangeScene method to teleport your actor to the new scene.