It sounds like they're recruiting for both the 742 and 744 in Europe, with the most likely bases being LHR and FRA. FRA being 742 only.
Starting pay for UK F/O is 41,000 pounds, plus (I think) 100 US dollars a day duty pay.
Once you join pax S/0 or freight F/0 you get a CX seniority number which you keep for the rest of your career there.
No your not employed by ASL. You are employed by a wholly owned subsidiary of CX on the freight fleet, but you get a CX seniority number. So it's slightly different from the ASL days, and a LOT better apparently.
Hope that helps