You have the ability to use the iDevice as a "flash drive" - plug into computer with USB cord, close iTunes if it opens, open the iDevice "to view files" on Win7 (a popup appears with multiple options)... or go into My Computer and click the drive that shows the iDevice.
Click the folder that appears, keep opening folders until you get to DCIM - your photo folder on the iDevice. From there, you can delete, edit, and add photos using drag/drop from your computer. Very convenient. No extra app needed. Once on the iDevice, your photo collection will be backed up on iCloud (if you allow Photostream) as if you took the photos with the device.