Java vs C# is the wrong comparison to be making when it comes to what is "better" to develop on. What should be looked at is the JVM vs CLR. This is where the real power of these two languages, and the others that run on them, comes to light. Languages and libraries can be made, but if the underlying VM doesn't support certain features, no syntax will make up for it. And, in my opinion, the CLR is slightly ahead of Java when it comes to power, mostly because of the support for generics at runtime, whereas the JVM doesn't (Java generics are type erased at compile time).
Here is what I would do if I were in your position: 1. Leave your money in the car/at home. The less easy it is to run to the snack machine, the better. 2. Bring your meals. For 12 hours I would bring 4 meals, and eat 2 more meals at home. You want to eat small meals regularly to keep your metabolism high. 3. Drink enough to piss every hour. Not only will you be properly hydrated, but getting up to piss every hour is you getting out of your chair and walking. 4. Take the long way to everything, and never the elevator. 5. Do a set of push-ups and sit-ups every hour.