Sorry, I don't have the Dean book at hand.
The "New Grove online" article isn't as helpful as we might hope, having just a paragraph for all the pre-premiere details. It does confirm that he worked on the opera in 1873 before interrupting work for another project, and had engaged Galli-Marie by the end of the year.
On the Habanera, I'm working from memory here, but I've seen articles about the many versions of many numbers, the musical examples including a Habanera in 3/4 rather than 2/4, with a wholly different tune. That hardly seems possible to me, as the particular tango-like rhythm is surely part of the character of a habanera; so maybe my memory is mixing things up. But the objections to the characters were widely shared in early years, of course; and I can't see that the precise fitting of notes to voices would have been a factor at that point. I'd like to track this down, but realistically am not likely to do so very soon.