Track creation. Option-Command-N adds a generic track; Option-Command-A and Option-Command-S add an audio or software instrument track directly, skipping the track-type dialog.
Recording has two shortcuts. R and the numeric keypad Asterisk both start and stop recording, the same action either way.
Editor shortcuts need context. Transpose, quantize preview, and Flex toggling only apply once the Piano Roll, Score, or Audio Editor is open on a selected region; they do nothing in the Tracks area alone.
Global tracks. Shift-Command-A, Shift-Command-O, and Shift-Command-T show or hide the Arrangement, Movie, and Tempo tracks. These are separate from the per-track shortcuts in the main Tracks group.