In theory one should be able to use KE's published CHI-BOM fare routed CHI-SEL-BOM to route over the Pacific. This is not always for the faint of heart, but I've heard that DL.dumb will properly price US-Australia via ICN (way over the MPM, but follows KE's published routing), so it should be doable. This is one of those rare instances where I think getting it done online will be easiest. However, routing via NRT is probably a no-go, since you'd have to follow the KE routing rules. SEL-TYO isn't such a hard thing to do on a separate ticket, however.

Definitely no problem with that. I've got OMA-AKL//HKG-OMA (connections suppressed, stopover in NRT on the return) ticketed. It's also possible to have a stopover in an intermediate region. (I've priced out things where one end of the OJ is in Africa, the other is in the Middle East, and there's a stopover in Europe on one direction.) The only hangup with open jaws for DL is to ensure that the unflown portion is the shortest leg of the triangle, as MSPeconomist noted upthread.