I have been reading through some older stories from AustBT and I have a question about established airline alliances eg Oneworld.

I have been reading through some older stories from AustBT and I have a question about established airline alliances eg Oneworld. I am a little confused about the extent of these alliances, pardon my ignorance but I thought if I was a Qantas FF and I flew on another carrier such as BA or CX that I could earn points and status credits. Reading some of the older articles i.e. QF no longer codesharing with CX or BA on certain flight routes, why does this matter? So even if they are all in the Oneworld Alliance, there is rewards points only available for certain routes flown? Can anyone shed a little light on this?

If you are flying on a oneworld carrier then you will (generally) earn points and status credits. You should check the earning table for the airline you are flying on the qantas website. Go to frequent flyer / earning points / airline partners to see the earning rates. 

Be careful as some fares earn very little points (i flew airberlin and received 63 points and 10 status credits).

If Qantas is codesharing on a (for example, CX) flight, I understand it that you earn points and status credits as though you are flying on Qantas (however please correct me if i am wrong here)

As per the response above the SC are at generally very fixed rates for the class you travel in, i.e. discount economy, full economy/premium economy, business, first.  As the post above points out some carriers don't offer as many (or any) FF points for their cheap tickets. Qantas are very generous with the 1000 point garuntee. Also the cabin bonus and FF status bonus come with the code-share flights. So in essence there is some erosion of benefits if you book a discount economy ticket or u are a high tier FF once the code shares dissolves!