A. I think your disk has developed several bad sectors. Before you send the bad disk to a shop that specializes in data recovery, you might try copying your files from the bad disk to the new disk.
Regarding your Outlook personal folder, the fact that you can copy 75 percent of the folder tells me that a large part of the file is intact. Because of the linear nature of .pst files, you can probably open this file from Outlook and copy much of the data to another disk. To do so, first install Outlook on the new boot disk. Second, create a new personal folder on the good disk. Third, attempt to open the older personal folder from the bad disk. (Depending on the folder's size, opening it might take a while.) Fourth, assuming Outlook can open the .pst file, begin copying the contents of the old .pst file to the new .pst file. I recommend copying email messages individually or in small groups (e.g., on a folder-by-folder basis).