If I want to make my pictures go with a fast song and make two images flash back and forth with the beat... is it possible I can do this without adding multiple images one after another? For example, if I had one picture a, then i had another picture b and this is how I wanted the pictures to go: a; b ; a; b; a; b; a; b. Could I do this without adding 4 pictures of "a" and 4 pictures of "b" and instead doing 1 picture of "a" and 1 picture of "b" flashing back and forth?

No. Just copy the images and name them differently, like a01.jpg, a02.jpg, etc.

We're planning to add this feature. Good idea! Rock on!