Upon reassembly I struggled for a bit trying to align the center button and getting it to seat properly in the clickwheel hole (the button is completely loose and "floats" in the clickwheel). It seems that it had a preferred orientation and did not rest evenly if it was not replaced in the same position. If I have to disassemble my iPod again, I would make a little marking pen to make a make a mark across the clickwheel and button to note the original position, or better yet, use a couple of pieces of tape to secure the button to the clickwheel before removing the frame from the front case.
It was the first time I broke open my iPod, and I was a little fuzzy on what was going on with this step. To amplify use the lip of the small opening tool to catch the edge of the cable retainer and gently pull straight up. It should click when released. To get the cable reinserted during reassembly, it was difficult to juggle both halves of the case and have enough slack in the cable to insert it back in the housing. What I used and was very helpful was a surgical hemostat that I used to gently grasp the cable and manuver it back into the housing.
I have some jewlers screwdrivers, but the rail screws are super small, and even my smallest screwdriver barely fit. Don't drop them on the floor or you'll never find them, and when reinstalling, a slightly magnetized screwdriver or tweezers will really help. I used an LED headlamp and reading glasses (even though I don't use them to read) to align the screws.