I am currently booked on a NW flight from SEA-NRT for end of next week, but I'm concern about delayed/cancelled service caused by the possible (probable?) mechanics strike so I'm considering alternatives.

One of the alternatives I found was a UA flight #875 for SEA-NRT, but comparable Biz Class is pricing 2-3x more than my NW flight through my company's travel agency. However, this price drops significantly if I purchase a SEA-NRT-ICN itinerary on UA875/UA801...i think you know where i'm going with this...so here are my questions given these circumstances.

1) Can I purchase the SEA-NRT-ICN itinerary and just get off at NRT and not complete the NRT-ICN segment? My company TA says that i'll need to pay a cancellation fee & price differential if I do this...Is this true even if I don't tell my TA that I've done this or will UA contact my TA asking for reimbursement? I'm interested in real life probabilities more than possibilities...

2) Will Japan Immigration allow me to enter NRT if they see that my ticket should be continued onto to ICN?

3) I did read from previous threads that the UA reservation system will cancelled all subsequent flights after missing the NRT-ICN sector... Is this true if I purchase separate itinerary for the remainder of my travel...or...if my flight from NRT is on a different carrier...such as Cathay or All Nippon?

I would really appreciate your help with this...I'm just not very flexible with my departure date and routing...and I'm a frugal spender...even with my company's money. Thanks.