iPhone 5 overheating and battery drains very quickly
Are you using IOS 7? When using IOS 7 be sure to check your apps which are running in the background, but normally these apps are also closed after some time in standby. Be sure to update your iPhone to IOS 7.1. When you say your iPhone/battery heats up when loading there is surely something wrong with your battery. Your USB transformer might heat up a little, but never had an iPhone heating up when charging. Contact Apple Support, or your reseller. Probably your battery needs replacement.