Yes, you have it right for the carrier null. Note that you are not only wiring the pot to 10k, but also the emitter of Q2 - the junction of those two pins.
For the DPDT, notice that SW2a and SW2b are labeled on the schematic. These are both halves of the DPDT. If you look, they are kind of triangular shaped, with one connection having an arrow pointing out of it. Each half corresponds to one column of three lugs on the DPDT switch. The connection with the arrow is the middle lug, and the other two connections are the outer lugs.