How much websurfing, texting, phone calls, or whatever else are you doing?
From my personal experience if i am doing stuff on my phone, ie. Texting ALL day, or if i am running a CPU intensive app like a game, or similar your battery WILL NOT last long. The heat is normal if you are running apps.. that is the location of the CPU, right below the battery that is. Like any processor when it is being pushed, or not even pushed, when it is being used, it creates heat; This is why computers have the heat syncs.. On top of that, GPS, or other intensive applications will produce large amounts of heat.
My phone will last for three days IF i am using it sparingly.. but if i have the screen on full brightness and im running the internet or any other app at that, the battery will be shot within hours.. This is a powerful phone with one hell of a battery hog screen and processor.. This is why the android OS has control, and can underclock the CPU, to conserve battery life.
If you want the best battery life that will last, turn your screen brightness down all the way... it really isn't that bad except in the sun... and remove any "Live" apps or widgets which update them selves in intervals, like Facebook, twitter, any Social Networking Apps.. The internet browser is powerful enough to be ablet to do all of them.
Take off widgets you don't use...
Finally, just give the phone's battery a chance. Let it go through a few full power cycles, after doing everythign i just said.