"Writers cannibalize (consume, use) their lives all the time. They feed on their experiences and memories--as well as those of others..." What does this mean?

is it "means of nourishment"

the answer is: the start of world war i, and russia’s hopes of benefiting from it

during world war i russian joined due to in their current crisis they were being supported by france and the war was already declared to them by germany, they needed to maintain their political goal and leadership role in the balkans, and is the same feeling that this excerpt evoke the eager of maintain the land value.

i’m alive so yes and the author is a technique idiom