how to use moveit to control a robot arm on a mobile base

Hi, I have a turtlebot and a turtlebot arm (with some modification from the original one). I can control the turtlebot arm using moveit individually. I then want to put the turtlebot arm on the turtlebot and perform some navigation+picking&placing. I've searched and read how people did this but I'm still confused. Please help me with following questions: 1. I have the URDF model for the turtlebot arm and I used the moveit setup assistance to generate the control package for it. Now I want to use the arm on the turtlebot, do I need to create a urdf model of the turtlebot with the arm installed? I read this post regarding how to link the arm with the robot (https://answers.ros.org/question/228055/how-can-i-link-urdf-file-of-turtlebot-arm-with-turtlebot/), and it said I need to add following to the xacro file. Should I add this to the arm descrition or the turtlebot description? 2. How can I use the kinect input to avoid collision? More specifically, I don't know how I can inform MoveIt the transformation between the arm and the camera. Will the urdf model of the robot with arm solve this problem? Any help will be appreciated! Thank you!!!