Is this possible?

Is an AWC3 a circle trip explorer? If so:

According to technical rule sheet for circle trip explorer fares rule number 16 (2) (d) it is possible to upgrade to an AWC4. (could be rule 17 as printer run out of ink!)

rule 16 (c) (5) states can upgrade to a oneworld or global explorer.

I have taken 1 flight one my AWC3 routed Africa-Europe-Asia with only 3 flights on it issued by BA in CPT/JNB who told me that I could add segments/continents later.

Now trying to re-route and told by QF desk in AUS that no changes allowed once first flight taken AND by

BA in MRU that it can only be upgraded to an AWC4. (according to rule 16 (c) (3) this should be without the $125 re-issue fee as its First class, is this correct?

Which is right? I read the rules that I can upgrade to an AONE4 Af-E-NA-SWP-Af as long as I pay for the extra segments. Is this correct?

Question on ticket issue - BA in JNB state that the carrier that has the first flight must still issue the ticket but I understood that you can elect who issues the ticket now, eg as I am a QF FF and can theefore get through to them quickly I want my ticket issued by QF for ease of changes.

Question on taxes - Does the same itinerary vary depending on which carrier issues the ticket?