Question

How does changing sentence structure from long to short and choppy help build suspense

Answer 1

Well, if you think about it, if your sentences are super short, you get right to the point and we don't know any of the important details. 
Example: The dog died. (short and choppy)
Verses: The suffering K-9 limped along the alley, energy slowly dripping away. He walked in the rain, not noticing the puddles he was trodding through. At length, he reached his almost flooded dog house, where he laid down. His he fell asleep never to wake again, finally at peace.
Make sense? Hope this helped! Sorry for the depressing example ;)