Hallel of the Seder

From Halachipedia
  1. It’s permissible to say Hallel seated, however, it’s praiseworthy to stand while saying Hallel. [1]
  2. One should be careful to finish Hallel and drink the forth cup before Chatzot (halachic midnight), however, if one delayed one may make the bracha of Yehalelucha following Hallel. [2]

References

  1. Chazon Ovadyah (vol 2, pg 59)
  2. Chazon Ovadyah (vol 2, pg 124)