shift-arrows scroll one screenful in that direction (equivalent to page up or down)
option-arrows scroll all the way in that direction (equivalent to home or end)
Most buttons have command-key equivalents, and there are visual cues for which keys trigger what buttons. Simply hold down the command key and any button command-key equivalents will automatically appear.
esc (the escape key) or command-period is equivalent to clicking on a cancel button
help is equivalent to selecting “Help…” from the file menu