I am afraid their is no quick fix for this.
To get rid of the noise, dust etc your best friend is probably going to be the clone tool. Select an unblemished area of similar color to the bit with the noise, and clone it over the top. Do this before trying to sharpen the image otherwise you are going to amplify the noise in the image.
For sharpening you are probably best using the unsharp mask as it is more adjustable than other sharpen filters.
Their is a technique which will allow you to sharpen JUST the edges, I can't remember the specifics off the top of my head but it involves running the find edges filter on a copy of the best contrast color channel in your image, and then using that as mask for the sharpen operation, a quick google should find something similar.
For color adjustment if it is selected areas that are the wrong color then you are probably best creating a mask of those areas and using an adjustment layer. If it is the whole image then try the variations option, or for tighter contorl use an adjustment layer.
If you post a copy of the image we can look at it and make better suggestions. If you need more info on anything then shout and holla and someone will be able to help out.
[edit] Just found a tutorial for the sharpening
http://www.creativepro.com/story/feature/12333.html
Where it says duplicating a channel in your image works well, look at the channels and pick the one with the best contrast and/or the least noise.
CC