What foods are the best to eat during a competition? How much/often/what should I be eating in order to perform well throughout a decathlon? Is water best to hydrate or should I be drinking other sports beverages? Please post anything that would be helpful during a competition.

I am a 17 year old decathlete. I stand at 6' 4" and 195 lbs. I have only done one decathlon and my score was below average. My state decathlon championships don't take place until June so I have some time between now and then to step up my training. I wanted to know if anybody had any suggestions for long term training on each event in about a 9 month period. My multis coach knows the hurdles and throws extremely well and also has decent knowledge of the 400, 1500 and 100. My jumps coach is not present very often so my technique in the LJ and HJ is poor, although I have a broad jump of just over 10' and a decent vertical. I have a good PV coach and on a 3 step drag I can easily clear 9' 3". The throws are my strongest area. I have decent technique but am not very strong. In throwing, I am looking more for strengthening over technique, but technical help is always helpful. The events I need the most help in are 110m H, 400, and HJ. If anybody can give me workouts for any event I would be extremely grateful. Thank you!