Display topic as mark on rviz and mobile robot model too

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About the covariance topics there are already some discussions about it, see #q9295, this rviz issue on github and this blog. There seems to be a rviz_plugin_covariance developped for Fuerte but it's not available for kinetic, so you would have to build from source (if possible).

And also I have to display my mobile robot simultaneously. When I launch turtlebot's minimal.launch a rviz showed mobile robot topic

That's not exactly a topic, the robot model is defined by setting the parameter robot_description, in rviz the field Robot Model will simply read this parameter. You can find it when going further in the minimal.launch that there is the call to robot.launch.xml that will also call the launch file description.launch.xml. In this last file there are those two lines responsible for the definition of the robot model :

  <arg name="urdf_file" default="$(find xacro)/xacro.py '$(find turtlebot_description)/robots/$(arg base)_$(arg stacks)_$(arg 3d_sensor).urdf.xacro'" />
  <param name="robot_description" command="$(arg urdf_file)" />

Just as a note : You also need to use the nodes robot_state_publisher and joint_state_publisher if you want to use TF. They both read the parameter robot_description to generate the TF.

I'd like to display it on my customized rviz field, not on the amcl's field

Can you clarify what is rviz field and amcl field ? Are you talking about the launch files ?