1)
What was the "Misgeres"? Where was it placed?
2)
Why does the Torah repeat the command to make a Zer Zahav for the Shulchan?
1.
Rashi: The current command is not to make a Zer Zahav, but to place it on top of the Misgeres.
2.
Bechor Shor #1 and Hadar Zekenim #1: Because it served as a Zer for the Misgeres which was made of wood, and which the golden Zer covered.
3.
Bechor Shor #2 and Hadar Zekenim #2: The Misgeres was made of gold, and what the Torah means is that they should make a Zer one Tefach thick to serve as a Misgaeres for the Shulchan.