1)
How did Moshe place the Mishkan (the lower curtains) before the boards?
1.
Seforno #1: People were holding them.
2.
Seforno #2: They remained in place miraculously. They were the main objective; everything else was for their sake!
2)
How did Moshe manage to put up the Mishkan, which was ten Amos tall?
1.
Rashi (in Shabbos, 54b): The Pasuk can be translated to mean that Moshe erected himself to the height of the Mishkan. 1
1
Refer also to 39:33:1:1**.
3)
What do we learn from "Es [ha'Mishkan]"?