Once you have set all the properties in Motion like scale, rotation etc for one picture you can
right click on that picture in the timeline and copy.
Now select all the other pictures, right click and Paste Attributes.
the only problem with that is that some of the pictures are different sizes to begin with, so changes to one picture wont necessarily work for another
Nest all your pictures and use the crop effect on the nest.
Not to take this too far in another direction, but if you have Photoshop, it is possible to create an Action which would resize all of the images to have the same dimensions. or if they are different shapes, at least have the same dimension in either height or width. It could do this to an entire folder at one time.