If the friend were to stay with double then the cheap SP8 adapter should be enough and still preferred over the K-Series. If the friend ever went to go to triple then the Birdy one would be preferred.

As to FD, the friend might consider a used Ultegra off Ebay, though they might be more expensive in Europe. I would just make sure that the cage is bolted rather than riveted to make experimentation with settings easier. In addition, I would advise getting the Sram adjustment washer to perfect the alignment of the derailleur cage with chainrings. It costs around $10, but once you try to make something similar yourself you are likely to decide that this $10 is a worthwhile expense.