According to this site, young voters did not support Le Pen (http://diversitymachtfrei.blogspot.com/2017/05/demographic-analysis-of-macron-vote.html).
Macron did extremely well in big cities and denseiy populated areas, in higher income areas, and with the more educated (https://www.ft.com/content/62d782d6-31a7-11e7-9555-23ef563ecf9a).
Maybe, but the EU is bit more secure now.This election may simply be kicking the problem further down the road. It does not bode well that Macron is younger than his average voter.
There was never a question of the Ultra-right winning the election as its support base is less than 40% so the EU is just as good or bad as it was before.
If those that dont like macron had done what some idiots did in the US (not voted for the lesser evil) then Le Pen had won.