Can my QFF number be used in a (non-FF) friend's booking?

Can my QFF number be used in a (non-FF) friend's booking?

No, they check that the name matches and even if you do share the same name you risk cancellation of your membership when they find out.

Okay, I understand that. Is it then possible to book for someone else using my QFF account and payment, or is it prohibited in both directions?

Reward seats, including points & pay, can only be purchased for other people based on following relationships:

• Husband/Wife
• Parent/Step-parent
• Domestic Partner/De Facto
• Child, including foster & step-child
• Brother/Sister
• Half Brother/Sister
• Grandparent
• Grandchild
• Son/Daughter-in-law
• Brother/Sister-in-law
• Father/Mother-in-law
• Uncle/Aunt
• Nephew/Niece
• First cousin

This is a fully-paid booking, though.

You can make and pay for a booking for another passenger from your FF profile,  as per QF website "name must match the photo ID that will be presented at check-in"  But you wont get the FF points.

Okay, cool. I'll get my mate to join QFF and reap the points for himself then.

I'm not sure that I understand your follow up question.  Perhaps if we knew what you are trying to achieve?  You cannot accrue points or status credits to your account unless you are the person flying on the booking.  Even if you have booked and paid for other people to travel and even if they are travelling with you, then you will only accrue points and status credits for your flying.  Further, you cannot attach your frequent flyer number  to another person's flight so that they get the benefits of any status you may have with QF (except for some very limited award upgrade exceptions if you are Platinum One).  As Peter said, you can use your points to purchase tickets or give upgrades to the relationships listed above. 

Okay, your answer covers everything I needed to know. Thanks!