It seems to me that Vader in Ep3 shouldn't have looked exactly like Vader in Ep5. Shouldn't Vader have had something akin to a crude Mark I outfit, then by the time he appears in Ep4 20 years later, there would be some advances in the suit to improve quality of life. He would then be wearing a Mark III type of suit.
It seemed more like they did this for the 'Look, it's Vader!' effect.
In fact, Ep3 felt a bit like 'The gang's back together' with the marketing, but I digress....
yes! the story of the prequals CAN be fit into 3 films. It goes as:
Ep I- parts 1 & 2
Ep II - parts 1 & 2
Ep III parts 1 & 2
ie: HP:deathly hallows, and the upcoming hobbit 2 parter. Of course it has to be done with a writer/'director who can pour his heart and soul into it and actually gives a damn about quality, story, and performance and not just $$$$ from merchandise. There was plenty of time to carve out a storyline for something of this size between 1983 and 1997(or whenever shooting for EP1 started). Each part could be 2hr30min long. I think fans would love it, I know I would. I think the time alotted would be enough for tons of entertaining, useful, creative ideas other than the tripe we actually got.
"There's no cluster of midiclorians that controls my destiny!" -Han Solo, from a future revision of ANH