Gmapping of custom robot

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I am going to do mapping on a custom robot. After that, give a coordinate on the map to robot and let the robot move there without laserscan data. I am new in ros. In this process, I still unclear about many steps.

1. When making the urdf of my robot, is it necessary to include a real kinect? Or can simply draw a box at the correct position?
2. I am using gmapping and i know it is required odometry tf. If i am using encoder and imu, how to convert these data to odometry? What kinds of data needed? For imu, the data publish as nav_msgs/Odometry or sensor_msgs/Imu?
3. After mapping, can i move robot on the map without kinect only depend on encoder and imu? The robot will moving on a static map which means no dynamic obstacle will appear.
4. After mapping, what kind of coordinate to be given to robot to move the robot? For example, i have a ball at 2d coordinate (x,y) and height,z. How can i pass the coordinate to robot so that it will move to the desired place?

Thank in advance for your guidance.