You can zorder a tilemap just like any Sprite.
(Keep in mind as far as I know you can't zorder individual tiles on a tilemap object,however. And that's where using layers would come in. You could have for instance the bottom on the tree on one layer,then the player as another layer,and finally the top of the tree as a 3ed layer)
you may want to turn certain objects in your tilemap into a Sprite and set the bounding boxes appropriately so that you can zorder them properly