Attack Range Increase

I know there had been much speculation in the past about manipulating attack range and so forth, but I was curious since I never bothered finding out the end result.

Is it possible to manipulate attack range via acquisition range (using an increasing acquisition range to increase the attack range or decreasing acquisition range to decrease the attack range)?

No. When you modify the acquisition range with triggers, that will only change the range at which the unit acquires targets, not it's actual attack range (this is how acquisition range is supposed to work). On the other hand, the acquisition range you set in the object editor will actually work as a cap on both the acquisition range and attack range, regardless of how you modify the first one with triggers and the second one in the object editor.

morph abilities are the only way to do this

Or upgrades, if you don't mind it not being reversible.

I've found no evidence that it's ever difficult or impossible to reverse upgrades/morphs applied by Chaos with another Chaos. Quite the opposite, in fact. Doubling Destroyer Form is the best way to avoid conflicts with other Morph abilities as well.