i can't speak on the peppers, but i recently made a chocolate stout by cutting the cherries from the black forest stout in Brewing Classic Styles. i used 8oz of toll house unsweetened cocoa powder at knockout in a 5gal batch. the chocolate was almost perfect, didn't overpower the malt. i don't know if i would go as high as a pound in a 10gal batch as the beer will pick up more chocolate flavor the longer it sits on the cocoa.
hope this helps!