I think it's just one method among many. For me, I like to watch as many mandarin movies as possible, along with TV shows (which are hard to come by with english subs), Chinese music, in addition to just regular study. But i also mix it up. Some classroom, some self-study, some mandarin learning games on my iphone, some audio lessons. I reckon the combination of all of these ultimately helps. I think music specifically will get you familiar with the way words are pronounced - a good one, with lots of clearly spoken lyrics, is Beijing Huanying ni - that theme song from the 2008 Olympics. Or more basic - Tian Mi Mi by Teresa Teng (or is that Tang?)

It depends on the song. Some songs don't make sense or use obscure Chinese characters that even native speakers may not really understand, but less useful in life. I recommend my favourite song Zhong Yu Ming Bai (终于明白)

When you have some basic knowledge of Chinese, Then I think that's will be helpful. Learn the lyrics and analysis the grammar, that's the way I learn English, really helps.

I don't think so, I never attach any extravagant hope to improve my English level by listening to English songs. The lyric have to rhyme properly, and some times they use words less to be understood and awkward to read. For a native, we can understand the metaphor, but for language students it's easy to make misunderstanding. Instead of listening to the music, I think watch Chinese movies and series is more helpful unless u watch them many times.

maybe not too obvious,mandarin can be short but exact,sometimes Chinese songs even more,and people don`t talk like that way,I suggest you can by listening the songs too improve your sense.