I don't remember well, but I think I have triggered that dialogue, since I did thought I could have the CC made once I had the Tears. I think even the pedestals aren't there if gone before you're suppose to but I may be wrong there.
As for the second question, I don't think you can have Serge regain his body before fighting the dragons, since you need Steena for Home Fort Dragonia, and she only joins once you have the 6 Relics you get from defeating the Dragons.