Sorry for double post, but to update:

The Dragonair lounge IS open, but empty. However, it is very close to the boarding gate of this night's QR flight - don't know if the QR flight leaves from the same gate usually?
Food options very limited, but some dim sum on offer, which is nice.

Entry was not too much of a problem after repeatedly pointing to the oneworld portion of the FF card... (lounge attendant was puzzled at first, so I'm guessing not too many QR passengers venture into this lounge..)