What exactly did the top curtain comprise?
Rashi #1 (according to R. Nechemyah): it comprised one curtain of ram's skins dyed red and another curtain of Tachash skins on top of it.
Rashi #2: (according to R. Yehudah): It comprised one curtain made half of ram's skins dyed red and half of Tachash skins. 1
It is not clear however, why the Torah then inserts the word "u'Michseh" (See Rashbam).
What were the measurements of the top curtain?