Hi Mark,
You can sing a melody and have BIAB record it. From this recording, it is possible to do the following.
1) Have the audio melody converted to a MIDI melody.
2) By tapping the speed of the melody on BIAB's tempo detector, it is possible to determine the melody's tempo.
3) BIAB's "Reharmonist" feature will add chords to a song. Recently, I did some investigating of this and found that these chords are best thought of as suggestions. When I tried Reharmonist on a few of my melodies, I did not obtain a chord progression that I was 100% happy with. I needed to change chords in a number of places to get a result that I was happy with. I recently posted about this at the link below. (The information in the entire thread at the link below is well worth reading.)
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=821642#Post8216424) BIAB does not automatically select a suitable style. It is possible to filter the style list in many ways, though, so that the number of choices are narrowed down. For example: filtering by tempo, genre, a swing style or even style will narrow down the options significantly.
Regards,
--Noel