This Airport card fits PCI-X PowerMac G5 and the Bluetooth module looks like one of those.

As for the antennas... You don't really need the overpriced original Apple antennas. Just get an MCX (one male and one female) to SMA adapter and a proper SMA antennas and you're done (at least that works for me).

I got that adapter really cheap here (about 5 EUR) and an antenna for another few EUR (mind you, if you use exactly the adapter I've linked you'll need a male SMA connector antenna while most of them are RP-SMA female ones) and that saved me like 50 EUR for the original antenna while works as good as such (or so I think).