I am curently pagbaba The Host and was wondering if i should read the bonus chapter in sequential order: between chapters 58 and 59, or wait till im done with the book then read the bonus chapter incase it gives anything away i havent learned yet?

I read them in order they appear in the book not in sequential order and I would recommend doing that. You will find out things you don't know but it is from when it is difficult to tell the story from Wanderer's perspective. I got the full emotional impact of the story pagbaba the bonus chapter after the rest of the book.