I wish I could help you, but I have been applying to FCX for 5 months now. I've submitted probably two dozen applications, and have yet to hear anything back.
Advice from someone who actually managed to get a job through their online system would be appreciated. My hunch is that you pretty much have to know someone on the inside to get a job at any of these big mining outfits. I've spent hundreds of hours applying to various mining companies, and they never respond.
In other words, if you don't know someone on the inside, forget it (at least in this economy).