While wirelessly syncing my 8700c today I received a call and just answered it, and while I spoke into the headset the person's conversation was coming through my laptop speakers. What is THAT all about?

That's because a computer can behave as a Bluetooth headset or speakerphone for your BlackBerry.

It's rather neat that you can do that. If you prefer to answer via BlackBerry, I think you need to disconnect the connection before answering the phone (I think it's as simple as pressing a key, not sure which)

During a call press the track wheel and then select transfer to handheld. (If memory serves me.)