I booked business class MAD-LHR-SEA-MFR through BA. LHR-SEA was on American, a route AA has now cut for the summer. The reservation is a mess so I'll need to call in.

Three questions:
1. Can I suggest any oneworld flights or will they try to put me on BA flights? MAD-LAX on Iberia and LAX-MFR on Alaska would be ideal.
2. Does BA usually allow changing the date by one day in this kind of situation where advance cancellations have mangled the itinerary?
3. Does being oneworld sapphire matter at all in this situation?