All very well having an intercom, but if all you get across it is "mumble mumble mumble MUMBLE ARGGHHH!" doesn't help much!
Not completely sure, but I think that's the Bike approval. To be really sure you need one that's BSI BS 6658-85 Type A approved, or FIA approved as that's what track days in theory insist on. Can't see them checking in practise, but you might as well get a Type A approved one. They're all probably as good as each other, it's just that some of the bike ones they won't have bothered submitting it for anything other than the bike approval test.