Thank you for your help everybody
It seems like Excel isn't able to deal with the quotes !
So I followed your advice and used LibreOffice, and it worked at first attempt, without doing anything on the csv file directly issued of Calibre !
When the content of the comments field starts with a quote, when a field is empty (resulting with "" in the csv file), Excel is lost !
Just for the fun I tried the calibre-db list command with the ¤ as a separator and with all fields, and it worked directly in Excel, but the result is less clear than in OpenOffice (like all the html tags in the comments field, or the tags in the form [u'tag1',u'tag2'] etc...).
Conclusion :
In my opinion, nothing has to be changed in the way the catalog export is done in CSV format, but a new txt export format could be developped, offering the choice of the separator and the surrounding field character.
Anyway, thank you for this wonderfull program... and its comunity
(sorry for my bad english too)