I don't know the 1st option by the street names, only where to turn off. I would think going from Nord to Est you turn up the street where you see the Mac Donalds, hang a left. You'll see the Est in the distance. That route I would say is longer. I use it when I want to avoid the stairs, dragging up the roller suitcase and carrying it down.
Option two is shorter, takes ca 6-7 mins. When exiting Nord, turn left, cross the street (the Albert I hotel is at the opposite corner, then take a left where you see the auto repair shop. There are signs pointing to Est. Then turn right right until you see the big spiral staircase. When you get to the bottom (this is where you could run into the petition signers types blocking your way at the foot of the stairs. ), Est is on the left. That is Rue d'Alsace entrance. On the left is the waiting room, on the right as you cross the entrance are mail boxes. That's where I drop off the last minute postcards.
The trains going from Est towards Metz, Lux. and Germany are only a few feet from the waiting room on your left. Basically, you are right there once you enter Est at Rue d'Alsace. If the EuroStar is on time (every time I took it, it was), once you're off the train, the whole walk to Est should be no more than 10 mins. That's the advantage of Est: train platforms for Germany are right there.