Is 70 minutes enough time to get from the Gare du Nord to the Gare de Lyon coming down from Amsterdam. Via the Metro?
According to my online transit map, you could take the RER D train - 7 minute trip, trains every 6-10 minutes: https://www.transilien.com/en/page-lignes/ligne-d. Um, it was showing that, but now it’s showing that you ride one stop on the RER D, then switch to the RER A, 9 minute trip.
Yes, it is enough time. RER D is direct between the 2.
If you buy your ticket from SNCF, make sure to buy from Amsterdam to your final destination: this will make it easier to take another train in case of delay on arrival in Paris.
It looks like the A train leg is temporary due to some sort of protest.
Yes, transit strike today.