iPhoto will only backup the images that have changed since the last backup. Keep in mind that if your image is 10 MB, then 10 MB of data will be backed up.
Things in iPhoto will not be backed up until after you have quit iPhoto, even though Time Machine may be backing up other data in other applications.
I do not know how iMovie or Final Cut Pro work as far as Tme Machine backups. Might be a good idea to post in those forums to let the experts there answer. Couldn't hurt to get some input from the iPhoto guys as well, as they answer Time Machine questions frequently.
If you are not already doing so, you would probably want to consider making separate backups of each library on a regular basis on another hard drive.
Earlier versions of the Mac operating system allowed a user to go into the iPhoto backups, select and restore an individual photo.
Unfortunately, that all changed a few years aglo. Now you must restore the entire library.
See the pink box in this document from Time Machine expert Pondini for all the gory details: