"A straight forward throw from ex. an ushirowaza" and "iriminage but grab uke's collar by the neck and make a reverse tenkan" I believe are both kokyunages.
Rokkyo is as you have described, but my Sensei has said that that name is not often used (at least in his experience) and it is refered to as something else. I think Katagatame, but I could be dead wrong.
The body turn to a choke sounds like (as it has been taugh to me) a similar motion as kaitennage. The actual name sof chokes, however, I have not been explicitly taught.
Best of luck on your kyu exam. Gambate.