^Right at CS2, multiple artboards was still a future feature.
As for clipping masks, it depends on what you mean by "edit clipping mask." To edit the masking path, click it with the Direct Select tool (white arrow). To edit the contents of the mask, try double-clicking to enter Isolation Mode, which was first introduced in CS2, (so I'm not 100% certain it worked on clipping masks yet). If that doesn't work, temporarily release the clipping mask, make your edits, then re-activate the clipping mask. (As long as you didn't bring any other object to the front, re-activating the clip shouldn't be too difficult.)