cpdude has got the closest to the truth so far.
Cpt Underpants, I believe the answer from Fire Wall about Nth American trips in reverse was in reply to the original question about HKG based rosters (these can be helpful for some...but really not applicable to new hires onto the freighter who are from/living in Nth America). Those who use the HKG based roster are mainly those who have been living in HKG already and don't need the housing allowance but wish to go onto the freighter in Nth America, or perhaps for some who come to HKG a few months before their Pax base officially starts to get set up and can handle life without housing allowance/schooling etc for a little while. The HKG based roster tends to be mainly HKG-ANC-HKG over and over again.
It is quite rare for any flights to go direct to HKG from Nth America on the Freighter. They do occur occasionally from YVR, but it would be fairly safe to say that 97% of freighter flights from Nth America go through ANC.
The schedules are varied and a tight pattern over to HKG and back can be done in 5 days. However, your average pattern will be 7-8 days. Very occasionally, you will do a pattern staying in Nth America.....more often from a reserve call out rather than rostered that way.
The JFK-ORD-ANC pattern is a stop in ORD for a few hours with some offloading and loading of freight and a pick up of a RPIC FO.
ie. it is 2 man crew to ORD and 3 crew continuing onto ANC.
hope this helps.