Hi,
Same problem here but SOLVED :-) (for now?)
At the moment I have only one album on my ipad, imported via iTunes, with JPG pics only (no raw)
I have the random order problem both while the pics were imported from an external HD as well as when imported from internal Laptop drive.
What resolved the problem for me was just deleting the "ipod photo cashe" folder from my laptop. (hmm strange that it is called IPOD photo cashe folder). (make a backup first, just in case)
then resync with iTunes (took only seconds)
iTunes then builds a new cashe folder
pics are now in the order I want them.
My photos are named by date (i allways name by date + number when I import pics from camera to Laptop) so if it ist true that iPad does not use EXIF info then it must have reorganized by name.
I hope this also works after i have imported more albums via iTunes to iPad.
good luck.