I, myself, am a college undergrad, and have frequently done a lot of DTW-NRT/KIX-MNL/BKK RT flights on NW. Here's what I figured out after all these years:

a. Given your travel date is on a Thursday and is not on a peak season, your chances of overbooking is low, unless there's bad weather. Peak time: WINTER, on Saturdays.
b. If economy is overbooked, and there are a bunch of business/first class seats open, economy class pax get upgraded at the gate agent's discretion.
c. ALWAYS, when checking in (luggage check-in), ask the gate agent if the flight is overbooked. If so, ask how you can get on the list. Do the same at the gate counter. [Sometimes when you don't expect it, the flight can be overbooked.] In Bangkok, I got my $500 voucher at luggage check-in, 2 hours before the flight when I arrived at the counter. In Detroit, you get vouchers at the gate, after the overbooked flight has departed.
d. If you fly back to Asia in December, particularly on a Sat (Dec 9 or 16 this year), there's a high chance of overbooking or operational upgrading.
e. When travelling from NRT to the USA (at least w/ NW), the Japanese agents usually don't give out vouchers. They prefer to reroute you and upgrade you, considering NW has a bunch of other flights departing to the USA within the hour. I think UA codeshares with ANA and/or JL to ORD and other US cities. There's chances of upgrading from NRT to USA, But don't expect vouchers. (However, business class upgrades are awesome! I heard that a one-way ticket from NRT - DTW in business class costs $3,000!)
f. However, from NRT to an Asian destination, they'll give out vouchers at the boarding area since the next flight out is the next day.
g. In terms of types of people airlines look for, volunteering comes on a first-come, "first-serve" basis. (They're serving me by either upgrading me or giving me vouchers.)

Little story to end: In early January, 1999, there was a snowstorm in DTW and a lot of Asian flights got cancelled. At that time, I was leaving Manila to go to Detroit. In Manila, there were 3 flights bound for Detroit -- all overbooked. I was offered $400 to take the flight the next day. I declined.

Once in Tokyo, my flight to Detroit was badly overbooked. I heard no annoucements asking for volunteers. Some paid economy pax went straight to the gate agent and asked about volunteering. The gate agent just upgraded their seats and put them into another city, with connecting flights to their intended destination. No vouchers.

I requested also to volunteer and was offered to be rerouted to another city and upgraded. No vouchers. I asked if I could decline the upgrade and get vouchers. Nope. I just took my original flight to Detroit. Lesson learned: Don't bet on getting vouchers at NRT when flying to the USA. Should have just given up my seat in MNL and ran away with $400 in travel vouchers.

Go Blue!

- Pat, Detroit resident, college student in NY, loves to pester relatives in Asia