iPhoto uses a database to store the photos and all the information about changes to those photos.
Backup and restore of any live database, or partial restore is much more difficult than the backup and restore of a full closed database.
I can only presume that Apple decided it was safer to remove the partial restore and browser functionality from TIme Machine and the later iPhoto versions.
This is from the link I posted.
quote " When using iPhoto ’11 (version 9.2 or later) and Time Machine with OS X Lion 10.7.2 (or later), iPhoto no longer has the Browse Backups option. This means that instead of restoring specific photos within your iPhoto Library, you must restore your entire iPhoto Library."
Further to that is the following quote
"Additional Information
Always quit iPhoto before restoring from Time Machine.
Time Machine canʼt do a full iPhoto Library backup when iPhoto is open. To ensure that Time Machine does a complete backup of your library, periodically quit iPhoto before backing up."
Time Machine is an excellent way to backup and restore your data but it should not be your only option. Consider having at least two versions of a backup,
1. TM that will allow you to restore different versions of your files.
2. A clone of your hard drive or drives that will give you a point in time exact copy of the hard drive that you cloned. See
http://www.shirt-pocket.com/SuperDuper/superduperdescription.html
http://www.bombich.com
Have the two backups ( TM and clone) on different hard drives, that way you always have two copies of your data, if your computer hard drive fails you have two possible ways to recover. The same rule applies to clones, close open files and databases before backup.
It does not answer your question on knowing your photos are safe but the only way to test a backup procedure correctly is to do a restore.
I would not recommend restoring over the software on your hard drive but if you really felt the need you could restore the clone to another external disk drive.
I am happy with my two TM and clone backups, yes that is 4 in all, I don't do test restores.
There are ways to recover a single photo from TM, it is not an Apple supported option and care needs to exercised when attempting it. If you ask on the iPhoto forum I am sure you will get an answer.