1) The cantor must stand when saying the blessing of Yishtabach, but everybody else does not need to stand. The Ashkenazic custom is that everybody stands, but the Sephardic custom is that not everybody stands. (Shulchan Aruch 53, Mishne Berurah and Kaf Hachaim)
2) The blessing of Yishtabach contains thirteen blessings, and one must be careful not to split them up. There is, however, no obligation in one breath, so that he can say it pleasantly. (ibid)
