Also, if you use the HTC Music app that comes with the phone, you can select a song to play, then go to Menu->Set as Ringtone to set any song you have on your SD card as a ringtone ( and if its long enough, you can trim it up from there. )
Also, using the usb cable, you can connect your phone to your PC to download any song from your PC to your SD card
So far, the phone has taken all of the audio formats I've thrown at it, even ogg.
Also, what kind of battery issue are you having? Have you been ignoring the battery indicator ( It is WAY off for awhile, until it can calibrate. Just go until the phone turns itself off for the first couple charges, then start charging at around 30 percent. ) What do you have on/off? Sync, Live Wallpaper, Enable Always-On Mobile Data, etc. What are your battery usage numbers? Settings->About Phone->Battery->Battery Use ( Including up time and awake time.. ), do you put the phone to sleep ( by pressing the power button ) every time you finish with it, or do you let it sit and put itself to sleep?...ohh, and how much time is it you are getting? Don't expect to go a full week
Even 3 days is pushing it, but probably reachable with fairly low usage.