issues with newest update battery draining quickly phone very hot iPhone 4

I recently updated my IOS to the newest edition. I do not know much about the techonological aspects of the phone and how it works, but I do know how to reboot the phone, reset the phone and close out all the applications so that there is no software running in the background.
Since updating the phone, I have experienced so many problems. The most unsettling one is that the phone is very very hot to the touch while it is syncing to my itunes and while it is charging.
I am not sure what is going on in the background, but currently I am in the process of studying for final exams and I dont really want to drive all the way out to see the Apple geniuses if it is something that I could possibly fix at home.
Also the battery is draining quickly as a result of whatever application is running in the background. I have turned my email off from push, it is now manual. I have also pretty much changed the setting of all the applications that use location or push for notifications because I am not sure what is making the phone run hot.
Any feedback would be amazing!
thanks
Iphone 4 iOS 4