There are big trees outside the window. You can see them when you lie on the bed. Is this good for feng shui?

Not good. You'd better move this tree, or it will affect you. Where the eight diagrams mirror should be placed depends on the layout of the room and the outside situation. Just hang the peach wooden sword on the bed. It is best to take a peach wooden sword to a temple full of incense and ask the monk to open it. Peach swords should be hung up, not under the pillow.