What does the Torah refer to as "ha'Mishkan"?
Which constituted the roof and the walls that housed the Aron, and the planks were there merely to support the curtains (Oznayim la'Torah, Pasuk 16). Refer to 26:15:2:1.
So-called because it housed the Aron, on which the Shechinah dwelt (Rashbam), or because it housed 'a 'chair, a table and a lamp' in honor of the Shechinah (Seforno).
How thick was each of the respective threads
Rashi: Each completed thread comprised each of the four individual threads (linen, dark blue wool, purple wool and bright red wool), each of which had been spun into a six-fold thread. 1
See also Ba'al ha'Turim.
What is the difference between "Ma'aseh Choshev" and Ma'aseh Rokeim" mentioned later (See Shemos 27:16)?
A lion on one side, an eagle on the other; a man on one side, an ox on the other (See Sifseu Chachamim).
What were the Keruvim that were woven into the curtains?