You can do all you have asked.

Just copy your important data files from drive C to drive D. If all of your data is in 'My Documents' you can move it in one to drive D. Right-click on 'My Documents', select properties from the menu and you will see a button marked 'Move'. Use that to move the whole folder to drive D.

You can also use the Files & Settings Transfer Wizard to save all of your settings to drive D before the reformat and reinstall on drive C.
All programs/Accessories/System Tools from the Start menu.