Thanks a lot for these precisions as it really was unclear for me.
By the way, you surprised me when you talked about Alf's Tools as I didn't know what was this tools. But, after a Google search I recalled that I was already using it (Only forgot its name)
I'm already converting some ePubs. Almost everything seems to be good, except that the mobi versions doesn't seem to have the same justification. Perhaps its impossible to have the exact same result, or the Built-in Calibre mobi viewer differs than the Kindle ?