MacBook Pro HDD corrupted files and bad blocks? Find command running for 4 days; Disk Utility reports no errors
In response to your first and easy question, yes, your HDD is dying and needs to be replaced ASAP.  Now is a good opportunity to change it to an SSD.  Here is a good video on YouTube that shows you how.

I am not sure why you would use dd to fix bad blocks/sectors when DiskUtility has a more robust solution.

Boot into recovery mode by holding Command-R (or off a CD or USB Key)
Go into DiskUtility and under the First Aid tab, click "Verify Disk"
You should get a bunch of errors reported
Click "Fix Disk"

Now, you aren't fixing the disk per se.  You are marking the bad sectors as unusable so data doesn't get written there.  

Once you do this...
Back up your files to another drive ASAP