I'm a fan of simplicity too. I opt for water and a sports drink like Gatorade at aid stations. I also consume energy gels with electrolytes during long runs. No need to overcomplicate things, as long as you're getting the basics right.
I'm a fan of starting at a moderate pace and gradually increasing it as I warm up. Helps me avoid burning out early and maintain a consistent pace throughout. Never been a fan of negative splitting, feels like I'm leaving too much in the tank.
Good advice above. I'd add that it's not just about changing your form overnight, it's about being patient and consistent. I've found that strengthening your core and glutes can also help improve your form. And don't forget to listen to your body, if you're feeling pain, stop and rest. Don't push through it, you'll only make it worse. Take it from someone who's been there.