Set the ScreenOrientation property for the horizontal stuff... You can set it to Unspecified, Portrait, Landscape, Sensor and User. Choose Portrait or landscape depending upon what you need. Sensor or Unspecified will use the device's default.
For the spacing of the buttons, use a Horizontal Arrangement and set the rows/columns to whatever you need. Then size the buttons. If you need more spacingon sides, use another arrangement or set of arrangment components to space things as you want...