Photoshop hints

Sharpen [other than in specific aresa for effect] and resizing, should be the last.
Working on photographs, I prefer:
Spotting [clone tool, etc]
Tonal adjust [Image adjustment tools]
Cropping
Final large area corrections [Brightness, Contrast, Curves] Save ‘master’
Resize for specific use
Sharpen [if needed for smaller size appearance].

In the tool bar for the Clone tool you will see a box and the word "Aligned". If there’s a check mark in this box, sampling point (x) will move as the brush is moved.
If the box is unchecked, the sampling point will remain where you initially set it.
Each time you click ALT, you re-set the sampling point.
If you want to clone over an area using the same sampling point for the entire area, make sure the box is not checked. For realism, though, you probably won’t want the same sampling point for a large area to be cloned. You’ll want slight changes in color or texture. Leave the box unchecked, clone some area, and re-set the sampling point in a slightly different place.

the new cs5 has an option where it can fill in those areas using the new fill aware tool.
a manual crop with the marquee tool would do as you ask, i am not aware of an auto one

Double click the background layer to make it a normal layer. Go to the Channels palette and click on the RGB icon while holding the Ctrl-key (Cmd-key on a Mac). That will load a selection based on luminosity. Choose the rectangular selection tool and while holding down the Alt-key, select the image itself. This will subtract the image from the selection, so you only have the shadow and he white background selected by luminosity. Hit the delete key to delete the selection.