Hello George,
The article you linked to regarding the law on hairstyles is slightly misleading, and it is a common misconception that this law abolished the topknot. The law actually stated that people were henceforth free to grow their hair in any way they choose. There would have been no rush to studios to get one's picture taken. (If there was a rush, it was just because photography was booming everywhere in the world at that time).
Note that merchants, etc.. could also carry knives, such as the tantō in this picture, for protection. They could also have topknots, just in slightly different styles from the samurai. So the presence of these things doesn't preclude the possibility that the subject is from a non-samurai family.
I think Uwe's photo above is quite good for showing the likely color scheme. I'm guessing the haori part of the kimono is dyed in ai-zome (藍染) style - indigo, basically. The tantō can be anything from the very garish to the understated. My guess from looking at the clothes is that the tantō would/should be a subtle shade: brown or black, rather than the vermilion or other colors one sometimes sees.