Correct. These services were QF7 outbound and QF8 inbound. all originated/terminated in Sydney and operated via Melbourne.

Also correct. I'm not sure of the Manchester frequency but by that time I'm fairly sure that the routing would have been Melbourne/Sydney/Singapore/Bahrain/London/Manchester and vice versa.

GIG is Rio Airport. Has been for as long as I remember...

I remember the QF7/8 as used to catch it to visit relatives in PER. QF8 for return. QF8 sometimes was pushing curfew in SYD if late through PER and MEL. MEL transited it in 19 minutes once (I've seen the congratulatory letter from the then CEO).

I seem to think MAN was done direct from another non-European port... Yes, QF9 went to MAN and QF10 originated there and went via LHR in the 90s eventually becoming a BA 733 MAN-LHR operating from the international terminal to T3.

I seem to remember the flight number for MAN was QF17 and QF18 in the late 70s/early 80s before it became a NAN/West Coast USA flight... I think it went something like MEL/SYD/SIN/BAH/possibly FRA/MAN or direct in to MAN on certain days... will have to look through some old timetables if I still have them.