Poor battery life and low signal are known issues with the phone itself. There are a lot of threads floating around with a lot of information about both.
To manage battery life (stock battery) I turn off everything except the auto-sync features I really need. I set screen brightness to half and turn on auto. Don't run wifi, bluetooth, or gps unless you need it. It has been established that gps won't drain battery unless an app is activity using it, but just to be safe. I would also get rid of any apps you don't use that might run or update often. I know the youtube widget is a battery killer because of how often it updates. There are also some really great threads floating around in accessories with cheap batteries and batter comparisons.
As far as low signal, it varies. It hasn't been a huge issue for me. Even on no bars, I can still make and receive calls and often have 3G still. I have read that changing radios can help sometimes. Also know that HTC is famous for a 'tinny' sound quality to their phones.