Yes, you will get access to the QF First Class lounge in Sydney. As Lindsay notes, The Wing lounge in Honk Kong (the CX facility) is the best airline lounge anywhere in the world. Make sure you enjoy it in both directions.
sprucegoose, there are so many things that we can probably help you with locating and using, however you have given us so little to go on, so I'll ask the questions to elicit the responses that we'll need:
1. Is it a paid F or Award?
2. Presumably you are a member of a OW FF program - which one and what level are you?
3. Have you been to HKG before??
As for details about CX's The Wing Lounge (quite a deal better than The Pier, like the difference between an F and a J lounge can be), look here. Take the virtual tour on this page for a better feeling.
As for the CX Manila lounge, definitely try it out. I've never been in it, but it couldn't be any worse than the pokey QF lounge there - see my previous report on Manila. QF and CX lounges were, last time I was there, next to one another...
Personally, I perfer the Pier rather than the Wing at HKG. As the Wing is kind of open (it's essentially the mezzanine level of the airport), the temperature can be difficult to control. Similarly, since the Pier is enclosed, it feels more private and less noisy.
You'll be going through HKG twice anyway, if you've the time, try them both! Along with the CX F service, there aren't many better ways to travel.