No, that is not correct about sexlinking.
With a barred father, ALL chicks should have white barring, males and females.
With a blue mother, chicks could be black or blue (either color being male or female, and both colors having white barring from the father).
The chick should not have a rose comb from any combination of those parent breeds.
Crevecoeur (mother) = V comb
Brahma (not-father) = pea comb
Barred Rock (possible father) = single comb
Bielefelder (possible father) = single comb
(I would have expected to see a v-comb on the chick, and I...
Generally yes.
(I've read that there is also a recessive gene for feathered legs, but the dominant ones seem to be much more common. Brahma-crosses almost always have feathered legs.)
I don't know about the gender, but I can tell you the Brahma was not the father. The Brahma would have feathered legs and no barring, but the chick has clean legs and white barring.
With the mother being Crevecoeur (black), the father could have been either the Barred Rock or the Bielefelder...