iPhoto 6 and Camera Compatibility

I recently upgraded my OS to 10.5.8 from 10.4... I know very late. I had no intention until the upgrade to my iPhone 3GS required it. Regardless, I am running IPhoto 6.0.6 and it has worked fine. I own a Canon T1i EOS Rebel digital camera. Up until the conversion to Leopard, I would plug the camera into the port and iPhoto would open up and transfer the pics without an issue. Today, I tried to upload pictures, the USB cord was secure on both sides and nothing happened. I turned the camera on and off twice to see if by starting it up connected would change things, nothing did. I ensured that the battery is charged in the camera and that the sleep setting was not tampered with thus not allowing it to transfer.

I am suspicious about the upgrade to Leopard causing this incompatibility issue with my camera. When I did a search on the apple website, the page about iPhoto 6 and camera compatibility is a dead link. So a couple of questions if someone would be kind enough to help me out with:

1) Is the import of pictures not occuring because of an incompatibility issue between my camera and iPhoto 6 suddenly? Or is incompatibility between 10.5.8 and iPhoto 6?

2) What is the best solution? Upgrade to iLife '11? Or will that require upgrading to Snow Leopard as well? Or is it better to buy the $129 bundle of Snow Leopard, iLife and iWork for compatibility issues?

3) Lastly, is there a webpage on apple that shows these compatibility issues? For instance, if I upgrade one thing in the future, all the other software suites that need updating as well?

Thanks in advance to whomever can help me.

Cheers,
-Tod