Hacham Ovadia Yosef ruled that when one recites Kaddish, it is proper for him to keep his feet together, just as we do when reciting the Amida and Nakdishach. The reason for this practice is to resemble the angels, who have but one leg. Certainly, one should not be walking about while reciting Kaddish.
The Kav Ha'yashar (Rav Tzvi Hersh Kaidanover, Germany, d. 1712) writes that even those who are listening to Kaddish should keep their feet together in their seats. However, this was said only as a measure of extra piety, and not as an actual requirement.
It is customary when reciting Kaddish to face toward Jerusalem, just as when reciting the Amida. Strictly speaking, however, this is not necessary. Therefore, when Kaddish is recited in a cemetery, and it is difficult to determine the direction of Jerusalem, one may face whichever direction he wishes.