My opinion on breeding is that there are more than enough out there, don't need another one.
Spaying and neutering, well there are a lot of articles out there at the moment regarding this.
Seems it can lead to cushings as the adrenal gland works too hard to produce the sex hormones the body still needs. As well it can lead to an increase in ailments in dogs. A study was recently done regarding the pros and cons.
Golden retriever study suggests neutering affects dog health :: UC Davis News & Information