Most camcorders that are hard drive or SD based camcorders work via USB transfer or (in case of the SD card) you can yank the memory stick and plug it into a reader to transfer the files.
Most HD consumer camcorders that are either HDD or SD based record in AVCHD. This footage will need to be converted before it can be used by imovie (or FCE). I use a Canon HF100 with FCE and it works well ingesting the media.
SD consumer camcorders that are either HDD or SD based usually tend to record in one of a few formats - custom for the camera (ie: JVC), mp4, or some other stream type file. These will also usually be converted to a format useable by the editor.
With HDD and SD based camcorders usually you won't need to worry about firewire as they have as I mentioned earlier, either USB access or just pull out the card.
Tape based formats will require firewire. There may be a tape based camera that offers a usb hookup, but I've never seen one myself (doesn't mean it doesn't exist).
tape based formats can only be ingested at speed of tape, so if you have an hour of footage, it's gonna take an hour.
SD or HDD footage, ingestion will depend on the original codec used, how difficult it is to convert it into the editors native editing codec, and how long the video itself is and if you're using SD, how good your reader is (cheap card readers can be slooooooow so if you're gonna get one, get a decent one, I've tried both my sandisk reader and a cheap one I had on the same machine and the cheap one took near twice as long. This here:
Memory Card Readers is an older test, but can give you an idea that between two card readers the speed can vary greatly).
Don't be afraid of conversion of video into the native editing format. I will say that converting for HD does take a lot of space compared to SD video, but the quality is incredible.
What I would look for (not in any specific order):
1) Capabilities - and I'm not talking gimicks. Record resolution, fps (there are some crap camcorders out there that record at less than normal speeds, but if you can find one that records at higher than normal as well, great 'cause that will make for some nice slow motion if you want it, but not really a requirement), etc. Things like special effects in camera - don't waste your time - that's what post production software is for. You can do all those effects and more at higher quality within FCE, and most in imovie as well (things like black and white, color changing, fades, etc.)
2) Hardware Look for imager resolution (who wants an imager with fewer raw pixels then the final video image (ignoring the concept of bayer pattern, which makes matters worse for a camera that uses an imager at a lower rez then the final video)) if you can find a 3CCD camera in a decent price range awesome (but they are rarer finds, panasonic AFAIK is the primary maker of 3 chip consumer level cameras (ignoring prosumer) but make sure to check reviews on video crispness, low light performance, noise, etc.), optical zoom capability, Autofocus capability (some cameras (and I'm not just saying cheap ones) have slow AF that tend to hunt especially in less then optimal light), if it has any form of image stabilization (preferably optical), external mic hookup, tripod mount, hot shoe, control position. Also if it has a viewfinder or just a screen; if just a screen is the screen clear/sharp enough? etc.
3) If HDD based, how long can you record on the HD? What "lengths" can you fit? Remember, the more you fit in a given space, the more lossy compression is usually used and the lower quality the material will be (so, if you have 2 camcorders both the same HD size and one records at its best quality twice as long as the other - you need to do research as to why so you don't end up getting something because it sounds awesome but ends up sucking).
3) Feel of the camera. Some cameras feel better then others in your hand. Some people like the camera being held in a horizontal format (where your palm is facing up and your fingers are going along one side of the camera wrapping around to the top of the camera) and some people more like the pistol grip style camera.
4) Battery runtime length. Some cameras have TERRIBLY battery time. Who cares if you can record 10 hours on the HD if the battery lasts 45 minutes? If the battery life of the camera that has every other feature you want is crappy, look for extended batteries that might be available.
You really need to make a decision on HD or SD as the prices, camera selection, record format, etc. are different and need to be evaluated differently.
Once you have figured HD vs SD, take a gander at some of the retailers to get some names and models of current cameras (like B&H, Calumet, BestBuy, Tiger Direct, Newegg, Amazon, etc.) then start researching - look for reviews of the cameras that interest you and really read what's said. Don't just go to one sight, go to several; also read user reviews and watch sample video from the cameras you're interested in with different lighting conditions.
I know it's a lot, but choosing a camera can be difficult (many cameras will have several of the features or qualities you want, but it gets harder to find one with near all of what you want), but if you find one you really like that performs well, then chances are you will be very happy with it.
Just my humble thoughts; I hope they help a little.
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