For the shadows on the faces, under Image-> Adjust-> Brightness/Contrast/Intensity this tool should resolve most of the shadows. Brightness and Intensity can do wonders for shadows. Also, you can mask off certain sections to brighten. This is particularly useful in high contrast photos (i.e. deep shadow, and brightly lit subjects) to mask off just the shadows. Since you say you scanned a slide, you will be amazed at the amount of detail that can be drawn out of even the deepest shadows.
Be sure the preview button is selected, you can also choose the double pane icon to see the before and after.
As for the dust and scratch removal under Image-> Correction-> Dust and Scratch this tool can sometimes work prety well, but as Javabear mentioned, you can end up causing more smoothing then intended, and blur the whole image.
If you don't like the clone tool, sometimes you can use the color picker, select a tonal area (3X3 or 5X5) and get a rough tonal approximation. Then use the smallest size paintbrush toget the job done (often times 1 point) then use the smudge tool to "smear" the colors together. The same result can be accomplished with the clone and smudge tool. This may be enough to get you started.
One last thing, don't be too critical if it isn't perfect. You must keep in mind what your final output size and resolution will be. This can often turn monumnetal disasters into barely noticeable imperfections. And then, 9 times out of 10, those imperfections are only noticed by you, and not your audience.