Also, a comment on your question regarding polow versus biryani. A former roommate I had, who was from India, told me that “biryani” refers to a cooking technique involving the addition of very thinly-sliced onions browned until they are very crispy and caramelized. The brown color of the onions changes the color and flavor of the dish, creating the “biryan”. I’m no expert, so I can’t vouche for that explanation, but I watched her do it with a lamb dish that she called “biryani” and which did not include rice.

Soaking helps with rice:water ratio and makes rice more tender. ~jaden