There is so much we can work on when mastering Freestyle. One aspect of the stroke that causes a lot of swimmers trouble is head position. Some swimmers tilt their heads up slightly either when they breathe or when their heads are in the water during their strokes. Some swimmers move their heads from side to side, never really finding that perfect alignment position. If any of my old coaches are reading the previous statement, they are all nodding along as I used to be extremely guilty of that one.
I once had a coach tell me that the best way to swim is to imagine yourself as twice the size you are. Over my career as both an athlete and coach, I've seen a lot of swimmers who swim like individuals half their size. What I mean is that they shorten their strokes, especially in Freestyle or as some call it Front Crawl, which causes them to lose out on some much efficiency in the water. One big idea that I try to get swimmers to understand is the notion of swimming like someone twice their size.
I've always felt that Breaststroke was seen as the lazy cousin to the other three IM strokes within the swim community. Some believe it to be the easiest stroke and the slowest. Unfortunately, I can't argue with you on Breaststroke being the slowest. Just the natural movements of Breaststroke make it slower and less streamlined than its counterparts, but this doesn't mean that it's for the lazy or is easy to do.
There is a misconception about the proper breathing for Butterfly. Many swimmers tend to come out of the water as much as they can when breathing in fly. This causes their hips to sink in the water meaning they have to expend additional energy to drive their hips back up to the surface. The result is usually a short pause between each stroke. That short pause, even if it's just for a split second, can throw off your entire rhythm.