Hi,
for auto task kills, you can use the "Automatic Task Killer" which is available on the market. It's a pretty useful application, where you can select/deselect programs that you want to be killed or not. The programs is very nicely to use. Every time, when your screen goes off, selected programs in the app, will be killed, and when you turn on your screen on, you will see a notification with information about released, and currently available free megabytes. ( you can disable the notification in app options ). The program kills the applications, even the phone is restarted ( unless you kill it, with another task killing manager

)
From my experience i know that there is a bug in the program, or it's may be a bug in the firmware (1.5), but when you listening music ( default htc/hero music app ), and you select to kill it in the program, when the screen goes off, the music stops, but when you turn the screen on, the lock screen, with the last played song will be there, and you cannot remove it ( at least i don't know other way to remove it ), until you reset the device. ( there is a way to remove the htc lock screen, i think in the forum there is a info about how to ). And one more thing - if you don't want getting late to job/school, always
uncheck the clock/alarm applications in the auto task killer.
Sorry for my bad english.