#4
The sustain part makes sense to me (puts it together for me) . I understand it now

Thank you!
#5
Avoid note is any note a semitone away from a chord tone. I feel that it is more dissonant when it is a semitone above the chord tone as opposed to a semitone below.


Also, avoid note is a bad term. Use with care is better. You can still use them and they can sound great.