Lidar with pixhawk

Am new with Mission planner and trying to build a quadcopter for indoor
Using RplidarA1 and pixhawk
Two things I want your guidance

  1. The object avoidance works on Altitude hold mode with the 360 degree Lidar and the parameters explained

If I wish to take off on Altitude hold mode and then the throttle reaches 50 % the mode of obstacle avoidance would be on ?
For Altitude sensing I have interface TFmini lidar at the bottom of the quadcopter and is sending distance