1. Your eating window should be 8 hours. Don't change the plan unless it doesn't work.
2. If you lift fasted, use BCAAs before/after. Use more BCAAs every two hours until you can eat.
3. Sprints have never really been addressed. I guess they are HIIT, but are they for fat loss? Not really the same as weightlifting. Personally, I don't bother with BCAAs on my separate sprint day.