first visit in two weeks!!

hi everyone :) i will be studying abroad in paris for the entire month of may, and planned a two day visit to DLP on may 11-12. i did the disney college program at WDW, so i'm familiar with the parks to an extent but i'm curious about what may be different. first, do people dress up for the parks in Paris? i planned on wearing a cute, somewhat fancy dress for at least one of my park days (i'm not worried about comfort, just don't want to stand out too much!) also, and i know this varies, how are the crowds on spring weekends? are there single rider lines? i definitely want to try to do as much as possible and i'll be solo on sunday. any other tips/insight would be appreciated (especially about the train ride from paris to the parks) thanks!!