Finding location of original photos in iPhoto

I wish to rename a series of photos in a specific order with more useful names (CC40_1, CC40_2, etc), where are the originals stored?

The originals were scanned in at a camera store. The shop grouped the photos for scanning. Each group has a naming convention of Name_Gp#_picture#.jpg, so several pictures in 'order' would look like this:

Taylor_1_001, Taylor_1_002, Taylor_2_001, Taylor_2_002, etc.

In Photo view, they appear in the order shown above, as expected. When I create an Album in iPhoto and arrange the photos as I desire, the photos appear in the order in the desired order, but only on my Mac. When they transfer to my iPhone and iPad via the Cloud, the album order defaults to the actual slide designation, ie. as in the examplw above. The same occurs when I use SmugMug to upload to a website. This is very frustrating!

I figure I will need to rename the actual .jpg name - captioning doesn't cut it. But I can't find them to do this.

Can anyone suggest a solution?