1) 1) According to the opinion of most authorities, these restrictions (cutting hair, music etc.) begin on the night of the seventeenth of Tammuz.
3) 2) One who goes to sleep on the evening of the seventeenth of Tamuz, and wants to get up before daybreak to eat, must specify before he goes to sleep that he is going to get up to eat before the fast. (As regards drinking, according to the Shulchan Aruch [and the Sephardic custom] it also needs to be specified before going to bed, whereas according to the opinion of the Rem”a [and the Ashkenazi custom] this is unnecessary. It is, however, correct to be stringent and specify even for drinking.)