Dan, I have no info on the vacuum system. A couple of other comments about the Jet 1642 are:
1) The power stays on to the speed control even after turning the lathe off. I fixed this by putting a on/off switch between the lathe and the wall outlet. Rockler sells them (router table switch) You still have to turn the lathe switch on and off due to the magnetic switch mechanism, but that is a good thing. If you ever have a power failure while turning, the lathe will not come back on as the power is restored. Good safety feature.2) The indexing system is not numbered like the Delta 1642. It makes it a little harder to index but not that big of a problem.
My neighbor has the Delta 1642 and I still prefer my Jet 1642. I also like the digital rpm readout on the Jet, which the Delta doesn't have. Also, the Jet headstock has a wider base than the Delta which is good.
Also, when you assemble the lathe, make sure you get the legs on correct, there is a left and right leg. The left leg has screw holes on the inside for mounting the basket.
Well I bet you're "turning" in your sleep (pun intended) while you wait for the arrival of your Jet. Good luck and happy turns. STeve Lewis