Up until Jan 01 2008 all FOs hired were designated freight only. Only other options to enter the company were as a cadet, or as a SO. DEFO with the freight designation was the only way to get into CX and have a base outside HKG, albeit on a lower payscale. Only guys hired from 01JAN08 and on that are assigned to the -400 fleet will fly freight and passengers. If you get hired on the 777, then passengers only as we do not have any 777 freighters.
You can turn down a city/jet offer to wait for a different basing, but I do not know how many times or for how long. As far as Europe vs US basing options, in recent history you would get into the company much faster if you were destined for a base in the US as the growth in Europe has been less than in North America. Judging by new routes and service (passenger and freight) I would say that that trend would continue. Only thing is if the attrition in Europe picks up due to better offers to current CX pilots. You can always start on a US base and then put in a base transfer request as soon as you finish line training.
FO