just got a rebel xt for $100 and am noticing some spots/dust when i look through the viewfinder. i'm the definition of noob when it comes to digital slr cameras. is there anything i can do to fix this? also on some photos i notice red dots on what i would call the left and bottom point of a crosshair. they're located perfectly where a crosshairs lines would end. hope that makes sense. thanks in advance, angelo