I'd also suggest protein. Something like a hard-boiled egg can keep your energy up without the carbo/caffeine crash.
Same here. Peanut butter sandwiches and OJ.

When I'm pressed for time, a high-protein power bar can really help. If I'm at home or near a Robek's or Smoothie King, a smoothie with protein powder is also a great pick-me-up.
Everyone is different, though. Another kind of juice or fruit might work better for you.
Also, in addition to working ahead on your school work, think about prepping food ahead, both so you can save time on food prep when you need to and so you can pack nutritious snacks/meals. Make things that involve good leftovers, especially leftovers that don't require reheating. My daughters are in college and very tightly scheduled with classes, homework, and various other activities. We have several dishes that they can pack in plastic containers and eat on the fly. Their current favorites are a cous cous and chick peas combo and a black beans and rice dish -- again, good protein and very easy to make and store.
YMMV, of course.