What is appropriate dress for Paris?

Being almost fluent in Spanish won't be much of a help for conversations in French. It will be very difficult to understand spoken language. However, for things in print - newspapers, menus etc. your Spanish will be a help. Almost 50 % of French written words are similar to their equivalents in Spanish. Don't try to overdress or be able to imitate French teenagers. When you do get to Paris, take the metro and almost always you will find groups of students going to or coming home from school. Just notice how they are dressed.