>...One question - While looking in the view finder, there is lots >of dust though not much of it is visible in the photos. Is it >due to a dirty sensor or something else?
Any dust you can see through the viewfinder isn't on the sensor. You're looking at the mirror through the viewfinder, not the sensor, so it's either on the mirror or somewhere else between the mirror and the viewfinder. You may be able to use a blower to clean the dust off the mirror (and the sensor too). Dust you see through the viewfinder won't show up in your photos, but it can be annoying anyway.