On my iBook, the hard drive was much easier to deal with than it appears in the Guide. My hard drive was connected to the board with a ZIF-type connector, held in place with a gray plastic bracket secured by two screws. After removing the bracket, I just had to ease the drive up and out. Then the gray plastic connector had to be pulled off the pins and transferred to the new drive along with the bumpers, etc.
As the other comments make plain, you can't overemphasize that the power connector is in tight, and it is much easier to pull the connector off the board. That's what happened to me -- I'm really bad at soldering, so I will be looking for a replacement board. Oh well.
When replacing the upper case, test the trackpad button to make sure it clicks before proceeding. If it does not operate properly, remove the upper case and reattach it.
When reinstalling, hold the display so the clutch cover is flush with the panel below. Make sure no wires are caught before tightening the screws.
In part 1, you can use a small flat-blade screwdriver to lift the locking bar. This will not put pressure on the cable itself. Each end of the locking bar will click when it has been lifted sufficiently.