Honestly, I have no clear idea. It could potentially be a poetic or metaphorical expression, but without further clarification, it's hard to say for sure.
Yes, it is. 'Mein Kampf' presents Hitler's ideology and personal views, making it a non-fiction work. However, its content is highly controversial and repugnant.
It's highly inaccurate and inappropriate. Mein Kampf is a highly controversial and repugnant work, and any manga based on it is likely to distort history and spread harmful ideas.