Calicos are Mille Fluer with too much white/mottling, yes.
F2 and F3 are not ratings, they're generations of brother x sister. F1 is the offspring of two different purebred parents. F2 is the offspring of the F1 crossed together, F3 is the offspring of two F2 birds.
There are people with them, but because they're actually a cull of the Mille Fleur, I'd think most owners don't stick around here much or ya just gotta wait.