The app connects through Google Chat. So in order to receive calls you have to go into your google voice account and forward calls to Google Chat. It should be one of the options in the voice settings. Other than that you really only have to enter your username and password. The rest of the options customize the app behavior or troubleshoot specific issues. I believe you can purchase the app from the market on your pc and then download it on your phone from the market app. The purchase is tied to the gmail account your phone sync's with, so you likely have to log in with that when you purchase from the pc. Alternatively you can purchase from the amazon app store. And I know that lets you purchase from a pc and download on your phone.