Depends on the class. I saw one class with 40% female another with 5%. Average is probably in your ball park of 10-15.
Yes to Bobby pins.
Usually, you wake up 30 minutes prior to the actual “wake up”, so plenty of time to put your hair up. I would often redo mine throughout the day because I would get bored in class.
I don’t know anyone that showered in the morning. There just isn’t time after PT, especially in those first 3 weeks of indoc. We were given 12 minutes exactly to change and be ready in uniform to get to breakfast. They give you a set amount of time, and they might send you to the sand pit later in the day. Baby wipes, baby wipes, baby wipes.
No, your hair does not have to be perfect, just within regs.
Currently, for the first 3 days of OCS you are running on limited sleep and you aren’t fed properly. For us, we got our first “real” meal the night before the IST. I think I was only given a breakfast sandwhich and 2 pb&js/ bag of chips as daily food the first 3 days.