From what I recall, the sticker was so that the groundstaff could separate transit pax from HKG exiting pax.
Clubhouse to gate is probably 5 mins or so, and I think you can see the SYD leg plane from the CH (I might be wrong on this and it could the LHR-HKG leg plane I saw).
Actually the 90 mins was a bit rushed by the time you get off the LHR flight and settled into the CH, and then you have to allow sufficient time so as not to get left behind. All this means that the CH break was a little too short for me. Mind you, I felt fairly shattered anyway!