Change of Itinerary
 

I have a round trip award flight booked with United (and partners) to JNB. I'm considering making some changes to the itinerary but I'm a little confused about how the rules work. If there's a stopover in the trip is an open jaw still an acceptable routing? Also, looking online, I can find certain routes (CPT-JNB-FRA-BOS) in economy but searching for the segments individually reveals that there are business class seats available on all the flights. Does this mean that if I call in, I should be able to resolve this?

Thanks!