The Laws of Prayer (The morning services) (19)

1. Even though in the ideal scenario one should stand while praying the Amidah, if a person is on a journey and unable to stand, he may pray while seated. Nevertheless, he should make an effort to stand at the points where he needs to bow down, so that he can bow correctly. He should also try to stand at the end of the Amidah in order to be able to take the three backward steps correctly. (Shulchan Aruch and Mishne Berurah 94)

2. Even when praying while seated, he should try to face in the direction of Eretz Yisrael, Yerushalayim, and the Holy of Holies. (ibid)