Best camcorder for under $2000...

panasonic tm700 has all that except interchangeable lenses, firewire and possibly lack of super slow-mo mode

for under $2k you probably wont get interchangeable lenses. you dont need firewire for transferring the footage to the mac. i dont know if it has the slow-mo mode

then chickenorfish's suggestion is a good one.

For better low light performance and with firewire, the Sony HDR-FX7 is worth a look. It doesn't do 1080p (it does do 1080i) and it does not have different frame rates. It seems like you want a prosumer or pro-grade camcorder. For under $2,000, there are none that meet all your requirements. Over $2,000, there are a few that come close, but may be missing the overcranking. The Canon HF S or Sony HDR-CX500 series all use a single CMOS imaging chip, but will be in the same general vicinity (video-quality wise) as the TM700.

Firewire is typically used by camcorders employing low-compression, high quality, video formats (HDV, HDCAM/XDCAM, DVCPRO HD). Most commonly, these DV-port equipped camcorders record to digital tape - but the camcorders may be compatible with external storage devices (Sony makes one for their HVR/HDCAM/XDCAM series; and Focus Enhancements' FireStore series are examples).

There are a few examples that are exceptions to this like the Sony NX series and HVR-Z7; Panasonic AG-HVX200; JVC GY-HM series, but they are outside your budget.

Not too many new camcorders in your price range running with CCDs. Most are CMOS imaging chips these days.

If you end up with a (typically consumer-grade) camcorder that employs AVCHD compression to MTS or other format files, these generally record to internal flash memory, replaceable flash memory (class 4 or higher SD memory cards) or non-user replaceable internal hard disc drive. As well, generally speaking, these camcorders do not have a firewire port and will connect to your Mac with a USB cable. To fully understand the connection and process flow, it would be helpful to know which iMac and what you plan to use (iMovie, Final Cut or something else) to import/capture/edit the video.

Your other option is to investigate some of the higher-end DSLR systems. I *think* they are all single imaging chip systems, but you said this was not essential. Their audio capture is not so hot, but that's not on your requirements list. Nikon, Pentax, Sony and Canon are the usual suspects - there are others. The Nikon D90 comes to mind. And audio can be recorded separately. There's also the Casio EXILIM Pro EX-F1. Some of these record to h.264 MOV (QuickTime) files.