1. Seiraku Feu modulation. (well, it's actually a natural minor key) or Yale Feather. The former is because it is good to write, popular music is more folk sung, but also fit the "family background" of the poem. The former is because it is easy to write, and it fits the "family background" of the poem. It was originally a poem by Wang Wei, who saw the folklore and sighed with emotion. The latter is due to the variation #4 in the elegant music, which will give the song an ancient flavor. (I admit that it is a "bias" born from watching "Legend of Zhen Huan" and being infected by its music.)
2. The timbre is more ethereal. But it's not a gas. ......
3. 4/4 time, medium tempo, a combination of one-beat and dotted notes.
4. Not quite understand ...... Acacia into the hand, the song set lingering.
Well. I hope to give you some reference it.