Yes, do take advantage of having a friend with access and guesting rights to the CX F lounges in HKG. IMHO, these, together with QF F lounges in SYD & MEL and JL F lounge in NRT (not tried HND yet, will be there in next spring) are the best Oneworld lounges. Just be aware that you might catch premiumloungeitis, a chronic disease, with complications such as excessive flying and much more.

Oh, welcome to BAFT, starting your career here with a relevant question. There will be one or two of Their Excellencies BAFT Ambassadors, to give you a more formal welcome. In the meantime enjoy the gold mine of information in the sticky "Dashboard" thread at the start of this forum.