Hey, congrats on getting probably the hottest phone in America right now! About battery, there is absolutely nothing to fix this. In plain terms, it sucks. Heavy Users charge it @work, @night, and in the car and it still sucks. Some Android apps are built in and can't be removed. In plain terms, if you don't use 4G at all, hate the extra fee, need long battery life, but love the phone's features get the Verizon Droid Incredible. If Sprint is a must, and you need andrioid get the Samsung Moment.
If you can live without Android., get the Blackberry Bold of Palm Pre
By the way, flashing is moving you're phone from one carrier to another. Since sprint uses CDMA, you could in theory flash to Verizon, Metro PCS, or cricket, but really only MetroPCS and Cricket. It's not worth it unless you LOVE the phone and know what you're doing as you could ruin the phone.