Nope, no aerating or dethatching, just scraped it lightly with a leaf rake. Mind you, my ground/soil was already fantastic. Because the initial cut is quite low, I cut it once the new grass was established, and cut the whole thing on a high setting on my mower, it may have juuuuuuust trimmed the new grass. Be sure your mower blade is VERY sharp for this cut, otherwise it will just rip and tear at the new grass.
I did mine in the fall for the reasons stated in the link. As for doing it all at once or in stages, depends on if you want to get a start on the first section in early fall, second section late fall. Not sure where you are located, so a lot depends on your seasons, first frost etc. If there are any turf farms in your area, you can always call them for advice.
Thanks for the compliment