From what I have read in the past, blondes ( natural ones) have more hair, and they also lose more hair on a daily basis 50-100 strands a day. Blondes have some 150,000 hairs. Brunettes have about...
At home box color usually has very high amounts of ammonia and sidekicked with the developer that is used with the hair color opens and swells the cuticle of the hair shaft. Thus resulting in damage.
Sure you can, you just need to rest to hair for a few days before you have it dyed. visit http://www.hair-color-ideas.net/right-hair-color-for-you for more info.