Because of the smoke would be above him in real life that's why it's practiced often in most places. As long as the fire would be above the window sill it could still be entered.
All personal preference in my opinion. I personally find it easier to transition from the ladder going in head first. Usually after the sweep at the window checking for victims and sounding the floor I would use a the tool I had and position it like the pike pole at 1:27 to use it like a rail to help guide myself in easier. I’m sure there are pros and cons to both but that’s just my opinion from my own personal experience.
