1) Sabre, bags, as clearly stated "May check baggage to".
2) What "new rule" do you speak of?
3) Makes no difference, if they interline, they can check the bags through.
#2, I looked it up, the released the hold on checking luggage to Europe.
#3 youre not right, there is a difference between if its ticketed on one ressy or not. Look it up.
On a side note, I am curious to hear from anyone else if they had success checking bags between BA & EK. From the research I did it didnt look like you can.