Lucas would be more traditional than
Luca in French. I'm not from
France, but I am Franco-Ontarienne, and although
Luca is definitely used,
Lucas is far more common. Keep in mind that
Luca and
Lucas are pronounced the same way in French.
Checking out the popularity lists for
France is probably your best bet. If you're interested in French Canadian names, there isn't a list for each French-speaking group; however, the province of Québec does have its own list (
http://www.rrq.gouv.qc.ca/Interactif/PR2I121_Prenoms/PR2I121_Prenoms/PR2SPrenoms.aspx). It's important to note, though, that there are English people in Québec just as there are French people outside of Québec.
Here are some young-sounding feminine names:
Léa
CamilleJuliette (
Julie and
Julia are also popular)
Clara (This name is adored atm, but it would depend on how old the character is)
LouiseCharlotteAmélie
MargotMaëlle
Clémence
Noémie
Émilie