[PapiPabs]

I'm not sure if the default is the same for all carriers, but the left convenience key should bring up Voice Dialing. If it doesn't and you want it to, go to Options-->Screen/Keyboard, scroll down to the Convenience Key Opens section (one for left, one for right), and change assignments to whatever you want from the list of available apps.

If you want to move the icon out of the Applications folder so it can be viewed as one of the icons on your home screen/one of the icons one level in after hitting the menu button, go to the icon in the Applications folder, click the menu button, select Move To Folder, and choose Home. From there, if you move the icon to the top row it will show up as one of your Home screen icons. (assuming you're using one of the default themes)