Greetings,
Sorry to hear about the lost pictures.
Does each camera have to have it's own iPhoto library?
Nope. You can import all you like. My guess would be that there was something wrong with the import process (bad data / corrupt media card in camera, low battery power during import, bad connection with camera, etc.)
Try finding the images on the computer using the File > Find in the Finder as described here:
http://support.apple.com/kb/TS1995 (maybe they just got misplaced / not fully imported into iPhoto).
Use the picture in that article as an example. Rather than having "Kind" "Any". Choose "Kind" "Image". This will locate any picture at all on your computer. You can then copy and paste the images into a new folder and then import that folder into iPhoto.
If you haven't used the camera since you deleted the pictures there is a good chance you can recover the images off the camera using data recovery software.
Here are a few examples:
http://joesoft.com/products/klix.php
http://www.prosofteng.com/products/data_rescue.php
http://www.macintosh-data-recovery.com/
http://www.subrosasoft.com/OSXSoftware/index.php?mainpage=product_info&productsid=1
You can contact a local Apple Authorized Provider to see if they offer data recovery services:
http://www.apple.com/buy/locator/service/
There are many nationwide / worldwide data recovery companies out there. Here are a few examples:
http://www.ontrackdatarecovery.com
http://www.drivesaversdatarecovery.com/
http://www.totalrecall.com/
Consider using these best practice tips to avoid or minimize the impact of issues in the future:
_Reformat the camera's media card using the camera itself between uses (check your camera's manual for how to do this).
_Ensure your camera has a full charge on the battery before you import (Or run off of AC if possible).
_Ensure the date and time on the camera are correct before importing.
_If you are using a media card reader and are getting regular failures, try using a different reader or the camera itself (The same is true about importing directly from the camera. Try a reader instead.)
_Plug the camera directly into the computer with a solid connection, no loose cables. Don't use a hub.
_Alternate between multiple media cards during photo shoots (trips, etc) so that if one card goes bad (they are just little bits of plastic after all) you don't lose the entire shoot.
Hope that helps and best of luck to you.
