Re: What's most/least important in music
These are what I recognise as the elements of music:
Timbre (what the nature or characteristic of sound is, basically like choosing the settings on a synthesizer)
Metre (basically time signatures, but to me it also includes rhythm grouping and phrasing)
I would like to add say that melody - which to me isn't a fundamental element of music - is a combination of pitch, harmonies, and most importantly rhythm, formed to make what normal people (i.e. non-musicians) call a tune.
Rhythm is the most important element of music (again, yay to us drummers), saying that rhythm is not the most important element in music is like saying that music can have no notes played at all.
Rhythm dictates how long a note lasts for, a note can't not have length, saying that it doesn't have length is like saying the note wasn't there in the first place. This rule applies to percussion, for example; a drumstick has to spend some time on the percussion object to make contact, if the drumstick doesn't make contact, there is no time of the drumstick being on the percussion piece.
I know I'm repeating myself but pitch, harmony, timbre, dynamics cannot happen without a note being there in the first place, rhythm makes the note fall in its place.