You can add you BAEC number to your QR booking via Manage My Booking, you will need your PNR (booking reference number) for this.

You earn both tier points and Avois for flights but you can also earn Avios for shopping (Pick and Pay is a partner in SA), hotel stays and car hire - more about that on the link I posted yesterday. Tier points reset at the end of your collection year while you keep your Avios as long as your account remains active.