Hi Widgeon
The reason the route goes back and forth across the States is to make up the mileage, asthere is a set distance you must travel. As you could just fly to one of the poles and around it, to have flown around the world! So they must remain below (South) of 60 North( I think !) and travel a certain distance, hence the back and forth to make up the miles.
I think the fuel load is about 450 Gals, ferry tank fills up the passenger cabin! and gives about 5 Hours endurance @ 120 Kts (Again I tjhink these are near, Simon did tell me, but my memory aint what it used to be,old age and all)
Regards
Hover Bover