RE #2 & 8
If you are using photoshop, no need to downsize to a piddly 640x480, you can still submit a photo with larger dimensions by going to the save menu and choosing "Save for web" and then picking "JPEG Medium" or "JPEG Low" when in the save for web interface. You can also resize the photo there. If you look towards the lower left corner of the save for web interface, you will see the estimated size of the file after saving - usually this esimation is accurate to within 1kb or less of the final size.