When should I use catkin workspace?

edit

I dont undestand why should I use catkin worksapce. When I export a package from Moveit Setup Assistant I move it on opt/ros/indigo/share and I launch it with roslaunch di/rec/tory/demo.launch. But the name of the exported package must be the same as the urdf package.

If I move the exported file from Moveit Setup Assistant to home/name/catkin_ws/src and run cakin_make and launch it with roslaunch home/name/catkin_ws/src/<package_name>/launch/demo.launch it gives many errors.

The question: Am I doing the right way or should I use catkin workspace?

Upadate 1: The error was because I was not running this command source devel/setup.bash before catkin_make . Now it works. But if I import urdf file to Moveit Setup Assistant it will load only if it is on opt/ros/indigo/share if i load the urdf file from local work-space the urdf package with meshes is not found.

The question 2: What should I install to local work-space catkin_ws/src (if this is the right path)?

Update 2: catkin_make fails when I install rviz_visual_tools and moveit_tutorials on catkin_ws/src
Info:

student@:~/catkin_ws$ source devel/setup.bash
student@:~/catkin_ws$ catkin_make
Base path: /home/student/catkin_ws
Source space: /home/student/catkin_ws/src
Build space: /home/student/catkin_ws/build
Devel space: /home/student/catkin_ws/devel
Install space: /home/student/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/home/student/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /home/student/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /home/student/catkin_ws/devel;/opt/ros/indigo
-- This workspace overlays: /home/student/catkin_ws/devel;/opt/ros/indigo
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/student/catkin_ws/build/test_results
-- Found gtest sources under '/usr/src/gtest': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.6.18
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing 4 packages in topological order:
-- ~~  - assem_moveit_config
-- ~~  - rviz_visual_tools
-- ~~  - moveit_visual_tools
-- ~~  - moveit_tutorials
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'assem_moveit_config'
-- ==> add_subdirectory(assem_moveit_config)
-- +++ processing catkin package: 'rviz_visual_tools'
-- ==> add_subdirectory(rviz_visual_tools)
CMake Warning at /opt/ros/indigo/share/catkin/cmake/catkinConfig.cmake:76 (find_package):
  Could not find a package configuration file provided by "graph_msgs" with
  any of the following names:

    graph_msgsConfig.cmake
    graph_msgs-config.cmake

  Add the installation prefix of "graph_msgs" to CMAKE_PREFIX_PATH or set
  "graph_msgs_DIR" to a directory containing one of the above files.  If
  "graph_msgs" provides a separate development package or SDK, be sure it has
  been installed.
Call Stack (most recent call first):
  rviz_visual_tools/CMakeLists.txt:13 (find_package)


-- Could not find the required component 'graph_msgs'. The following CMake error indicates that you either need to install the package with the same name or change your environment so that it can be found.
CMake Error at /opt/ros/indigo/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
  Could not find a package configuration file provided by "graph_msgs" with
  any of the following names:

    graph_msgsConfig.cmake
    graph_msgs-config.cmake

  Add the installation prefix of "graph_msgs" to CMAKE_PREFIX_PATH or set
  "graph_msgs_DIR" to a directory containing ...