ekf_localization_node : Filterd odometry yaw depend on IMU too much and Laser scan drift when robot rotate with filtered odometry.

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I have a odometry/filtered fuse by wheel odometry odom and IMU imu_data with ekf_localization. I let my robot facing a wall and do some test with the odometry/filtered. I have two problem right now:

Problem 1

• My odometry/filtered when I move the robot forward and backward, rotate the robot on the spot, the odometry/filtered output seem to be like good in rviz.
• https://gph.is/g/4wg9DPD The rviz output, green arrow > odometry/filtered, blue arrow > odom, the axis in front the base link axis is my laser axis.
• But when I lift the robot up to make the wheel loss contact with the ground and move the robot forward and backward, both the odometry/filtered and odom output in rviz will move forward and backward too. When I rotate robot on the spot without wheel and ground contact, only the wheel odom move, the odometry/filtered is not moving, this make sense to me because the robot is not rotating only the wheel itself is running.
• When I leave the robot not moving and rotate only the IMU, for sure the odom won't move, but the odometry/filtered will be move exactly same with how I rotate my IMU manually.
• Rviz output: When the robot lift up, first: Rotate the robot , Second: Move robot forward and backward, Third: Rotate only the IMU. https://gph.is/g/EvdnpAY
• Is my odometry/filtered depend too much on the IMU? And is it related to covariance? How to make a better configuration on this?

Problem 2

• When I rotate the robot with the odometry/filtered, my laser scan will drift when the robot rotate and the laser will back on right position when the robot stop.
• This is the rviz output when the robot is facing a wall and not rotating. The green arrow is odometry/filtered and the blue arrow is pure odomfrom wheel encoder. https://ibb.co/Y33m99M
• This is the rviz output when I set the laser scan decay time to 20s and rotate the robot. The laser scan will rotate when the robot rotate. https://ibb.co/TB3ZpmB
• Rviz video https://gph.is/g/ZnM9XNJ

ODOM topic

header: 
  seq: 42461
  stamp: 
    secs: 1560329405
    nsecs: 936365909
  frame_id: "odom"
child_frame_id: "base_link"
pose: 
  pose: 
    position: 
      x: -0.210383832846
      y: -0.0374875475312
      z: 0.0
    orientation: 
      x: 0.0
      y: 0.0
      z: 0.145501269807
      w: 0.98935806485
  covariance: [0.01, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01]
twist: 
  twist: 
    linear: 
      x: 0.0
      y: 0.0
      z: 0.0
    angular: 
      x: 0.0
      y: 0.0
      z: 0.0
  covariance ...