When (re)inserting RAM, the connector is tight - push firmly on both sides evenly - usually will "click" when fully seated. Look at the RAM connector edge - the gold should be almost completely within the socket (if not fully seated, it won't be recognized).

The foam on the harddrive is attached with an adhesive tape - be careful to peel up the tape from the harddrive, rather than the foam from the tape.

Note where the airport antennae connecting wire comes out from the interior along the top. When reassembling, it has to be routed the same way, or it won't reach its install position.

Be careful with the plastic knob that extrudes into the outer case (the PCMCIA card ejector). It's fragile!

They aren't kidding about the "large multi color" cable. A pair of hemostats and very careful wiggling will do it - NB: the lower portion of the plug, the white plastic holding the pins upright and separate, actually came significantly up, almost off - watch for that and (carefully, of course) gently press it back down - it sits flush on the board surface.

It may be helpful to note that there are two side by side - you want the one holding the bracket to the AirPort cage - it will be on the left as this picture is oriented. A little hard to spot under the edge of the silver shield...