Per the rules a disordered unit cannot change formation, but can use its formation change to eliminate the disorder. I assume this means that a disordered unit that uses its formation change to remove disorder cannot also change formation in the same action phase too, right?
When a unit uses its formation change to remove disorder it can't change formation too, right?
No. If a unit removes a disorder in the first segment, it can change formation in the second segment, as long as it's not disordered again.
Correct, it can't ALSO change formation that segment ... it used that 'time' to go from disordered back to its original formation. It can, of course, change formation in the next segment.