welcome to flyertalk!

it's nice to see someone who lays out a clear thought pattern rather than a too-general question

1. why fly anywhere else than ex-MSP? if you look on a globe, NRT is just up-and-over. going to EWR or even ORD or SFO is actually out-of-the-way. and, given the hazards of connections or delays, i believe you are just much better flying out of your home city on your local carrier

2. the NRT/PEK leg may be on a A330 (search for more info) but will not be a through flite on your original 747

the on-line connection times in NRT can be very fast-like an hour

3. on Mon, Fri, Sat (i believe) there is a second flight-NW3, just ten minutes after the daily NW19. so, you have a better chance of an upgrade clearing on that flight

4. but, oct 15-30 are the dates of the canton fair. most flights to china (i.e. even the lift via NRT) are full/overbooked, even a week before and after. so, you may wish to adjust your flight dates to a less busy time.

good luck!