It is. However, it is also an output drive. Since you can store information on a hard drive, as well as reading information from it, it is both.

Depending on what do you mean by "going bad".

just so you know, the slowest component of the computer is it's hard drive (because it's mechanical) , therefore, a bad hard drive will probably slow things down.

A hard drive recovery service should offer you a backup plan when they are done recovering your files. You should ask for a recovery disk, or at least a back up disk for when it happens again. Usually, these services will give you a discount if you bundle some services together, like a virus scan.

a hard drive failure is when your hard drive stops working...

a hard drive is called "disque dur" in French.