Headsets
If you end up on the Airbus Fleet, they use XLR-5 plugs, so you may need an adapter if you have the standard 2-plug headset.
(Google "Marv Golden" in San Diego, he carries them under Telex products).
A340-500 has noise canclling, the others don't.
If you end up on the Boeing Fleet.
The "classics" (777-200, -200ER and -300) come with standard headsets with 2 plugs.
The -300ERs and -200LR's have noise cancelling headsets, also with XLR plugs, but there are also provisions for standard 2 plug headsets on the 777, so you won't need an adapter.
Use of intercom is not standard procedure, so most guys (and gals) fly around with one ear half uncovered.