Q. A person is davening in such a way that to open the Aron Kodesh, one must walk in front of him. 
What should be done on Rosh Hashana or Yom Kippur when it needs to be opened numerous times? 

A. He could use his shtender as a ‘Mechitza’ or separation.
On question 3936 regarding why do people seat in the shul during the Hakofes of Simchas Torah, is it not prohibited to remain seated when a Sefer Torah goes by next to us?

To what we answered: “One has to stand when a Sefer Torah approaches (Shulchan Aruch Y.D. 282: 2). This applies even when one is occupied in learning Torah (Pischei Teshuva ibid. 3). However, if the Sefer Torah is being held or carried in a separate area of the shul such as the elevated Bima one is not obligated to stand (Shulchan Aruch Y.D. 242: 18).
The same would apply if one is seating in a separate area of the shul.

Horav Shlomo Miller’s Shlit’a opinion is that one may remain seated in need when separated from the rest of the shul by a full size common shtender (movable pulpit that holds a Sidur etc.). The Rov added that regular shtenders have the shape of a small door and is seen as a separation.”

The Rov Shlit’a added that one should fasten horizontal strings on the width of the legs of the shtender with a separation of less than three Tefachim (about 30 cm.) between them.

Rabbi A. Bartfeld as revised by, Horav Dovid Pam, Horav Aharon Miller, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a