I thought I had read something saying a brown dot on the back of the head indicating the Columbian gene? Is that true? If so does the gold dot mean the same thing?
Hmm, well I know that Wheaten-based Columbian-patterned breeds can have some black or gray spotting in their chick down, particularly in the head and on their back. Generally it looks like a thin stripe, though, not so much like a blotch. I don't think that the blotch on your chick has anything to do with the Columbian gene.
Thanks! I'm a little partial to them!

I am keeping very meticulous records on everyone I hatch so I can gather some data and stuff to look back over once I'm a few yrs in to see if I can see patterns to improve my breeding program. I am not sure if anyone is working on Ermine color variants or not, like lavender ermine, chocolate ermine, or blue ermine. I've seen a few birds that were culled out of Ermine lines for being blue ermine and they actually were quite beautiful birds
Sounds like a fun project! I know that the base Ermine in Ameraucanas is absolutely beautiful. I imagine dilutions of it like blue and chocolate would be gorgeous as well!
So at the I locus can a bird be only one of the genes you mentioned or can they be mixed with some of them? Like could they have both dun and smoky? Or be dominant white and smoky?
Each locus can have a two alleles of that particular gene at it. So at the i-locus, you could have a combination of any two of the i alleles, i+, I, I^d, or I^s, depending on what the parents have to pass on.
So yes, a bird could be I^d/I^s for both dun and smokey, or I/I^s for dominant white and smokey. I don't know how smokey interacts with other i-locus alleles, however, so I don't know how such a bird would look.
I've seen people say that blue expresses differently on male and females? Is this true? If so can you explain or show examples of how?
Kind of, but not to the extreme that male and female Duckwing or Wheaten differ, for example. Blue males get those glossy, decorative feathers in the hackle, shoulder, and saddle area as is typical of roosters, and these tend to be a few shades darker than the ground feathers, giving them an almost darkened saddle look, kind of like the saddle mark some dog breeds get if that makes sense.
Here's a picture from Cackle Hatchery that shows that difference pretty well. The male has those darker masculine feathers on his neck, saddle, and shoulders, while the female is only darkened a bit in the neck: