1-2.) Just a couple of headshots I drew while trying to pin down Downbeat’s design. She usually wears her mane loose but will occasionally tie it back in a low ponytail as shown above.
3.) Downbeat in an outfit she might wear to a more high-end venue - she usually just wears the bow-tie with the white collar during performances with her band. As for her cutie mark, I know that the alto sax typically reads the treble clef, but since Octavia’s cutie mark is a treble clef despite the cello typically reading the bass clef, I thought it’d be fitting to give Downbeat a similarly incongruous cutie mark.
Downbeat doesn’t have an official reference yet - I’ll update this deviation when I’ve drawn one for her.