-editable footage (mini dv I think) (edit with imovie) Yes, miniDV tape camcorders will connect using FireWire400. Yes, iMovie will control the camcorder over FireWire. FF, Rew, Play, Import, Stop, Pause... And yes, miniDV tape content in the camera will import directly to iMovie... but that does not mean that is the only "Mac Friendly" media.
-fire wire FireWire is only needed if you are doing transfer to/from a miniDV based camcorder. Hard drive camcorders use USB to transfer files. SD-card based camcorders can use either the camcorder's built-in USB or a card reader. You need to install and use StreamClip to read those files. Memory card camcorders capture files similar to hard drive camcorders. I would never recommend anyone get a DVD based camcorder (especially if they, like you, want to edit the catured video), so I make an effort to ignore their existence.
-hot shoe (for mic) I think Sony is the only camcorder company that has a "hot shoe" - they call it their "active interface". It is for Sony proprietary mics that can only be used with the active interface. The term "hot shoe" is typically a term for SLR cameras and mounting a flash - the "hot" is because there is power in the shoe for controlling the flash (but not necessarily supplying power for the flash to happen). I presume you want a mic connection for the video - if the camcorder has an external mic-in jack, the shoe does not need to be hot... Heck, you don't even really need a shoe because you can always add a camera bracket with a "cold shoe" to mount stuff. The lower-end Sonys with a proprietar active interface shoe can use an adapter (available only at B&H Photo, I think) that will allow connection of any 1/8 inch (3.5mm) mic jack...
-mic input (hot shoe or mic input is ok) See the response, above.
-under $400 The only one that comes to mind is a Vanon ZR800 - but be aware that it will need that cold-shoe bracket, is not so good in low light and does not have manual audio controls. See if there is anything else at camcorderinfo.com in the ratings (you can check the pricing column). The Canon Elura 100, is another one, but they are not very easy to find. The only Sony I can come up with is the HDR HC96, but it is outside your $. In addition to the camera, you *should* also get a tripod, extra high-capacity rechargable battery, good sturdy case, FireWire cable (4-pin camera; 6 pin computer - it is not included in the box, only USB cable is) and a video light...
-does not have to be brand new but quality would be nice I would not recommend a previously owned camera to anyone (unless I knew the seller personally and know how the camera was cared for).
-I do like sony but it is not a necessity. Mac Pro is a nice computer - why not a nice camcorder? Is this something urgent or can you save $ for a bit and move up?
May I suggest that before you buy a camcorder, you visit the apple.com support: iMovie: discussions area and search for the camera you are considering.
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