Both the wheat berries and barley should be soaked overnight and then cooked for approximately 1 hour.
If you’re a seminary girl invited out for Shabbos, and you’re a very particular, I think it’s just mentschlich to let your hostess know that you don’t eat X or Y. This way she doesn’t prepare for nothing and there are no hard feelings (especially if there are a few girls!).
I tested this recipe with cooked brown rice instead of the wheat berries and barley, and it was excellent. Loved the texture!