In Photoshop's preferences, you can select if you want something that you pull in to your document to fill the page, or come in at normal size. You might want to check to see if PSE has something similar.
As for resizing your photos, I recommend a keyboard shortcut. If you have your photo layer active and on your keyboard press COMMAND and T, this should put a boundary around your photo with little squares on each corner. If you hold down on the SHIFT key, you can pull or push those little squares to resize your photo quickly. You want to hold the SHIFT key in while you do this so the photo stays in proportion.
Hope this helps!