This Ableton tutorial from the Learn Live series covers two practical note-level editing tools: transposing MIDI notes and stretching them in time. It walks through both the Transpose window and keyboard shortcuts, giving you more than one way to work depending on how you prefer to move.
For transposing, you can click and drag in the Transpose window, or select notes (Cmd/Ctrl+A for all) and use the Up/Down arrow keys. Holding Shift with the arrow keys moves notes a full octave at a time.
The bit also introduces MIDI stretch markers, which let you stretch or compress notes within a selected time range. The stretch section is brief, but it points to a feature worth exploring further in Ableton's detail view.