On the "how important is musical taste?" issue ...
It is not important to me that someone listens to the same music I do. However, if someone does, it is definitely an indicator to me that they might listen to that music for the same reasons as I do, which is really really attractive to me because it means we can share the experience of listening to music by enjoying the same aspects of it. I personally listen mainly to slower, deeper, more psychedelic, more bass-heavy music as a general rule, and I do it because I like to feel overwhelmed by sound, and it is cool when a piece of music causes a reaction in me that I am not exactly in control of. I like music that takes me out of myself due to some aspect of the sound itself (reference points: the guitar solo in "Indian Bones" by Dead Meadow, or the bass drop in "Rutten" by Skream ... these specific moments in these songs consistently create physical sensations in my body and therefore alter my mind in their own way, and it's moments like that that I look for in music).
It's not that I want someone who has the same list of artists in their iTunes as I do. It's that I want someone who, when I am given a new experience by a piece of music, can share that reaction with me or at least sense what is happening in me when I have it ... in other words, someone who listens for the same things in music as I do.
I have trouble connecting on a musical level to someone who listens to music primarily for lyrics. Lyrics are generally last on my list of priorities when I listen to a piece of music, so someone who listens to music for completely different reasons from mine will probably not be able to understand why I listen to the music I listen to ... and that's more important than actually sharing interest in the specific artists I listen to, by a long shot.