In photo shop we can reduce a photo of 4mb into about 400kb. While saving the image after editing photo shop(not in 7) will ask the quality of image to be saved. Select a lower level.I use to do it for uploading photos in net.
It is the working area of a processor (in short)
Yes. But some cases "no" since it may affect their views to their society.
If you are not sure about opening it go for the cleaner CD it works fine no need to open and take risk .