Hello,
There is practically an overload in information about DV cams, and I'd thoroughly recommend a good search engine like Google. Everyone has their favourite, mine being the Canon MV20i that I bought last year.
I have read that some models (don't know which) have the
DV in/out port present, but it is disabled. Enabling can be done with some sort of button pressing combination, and others need a bit of wiring which could be a simple job. Could be risky though.
Sizewise, I would cauiton against going for the smallest, lightest, most pocket-sized camera, because it can be difficult to hold and manage the various buttons, knobs and dials. It might look good, but if you're either ham fisted or have big hands like I do, it will be a hindrance.
Depending on your personal use/need, I'd also suggest not bothering about having the
digital still function. My thinking is that these models that have cards for stills are good, BUT all they are basically are frame captures, which you can do on the PC. Afterall, it IS primarily a video camera. If you have a reasonable software package and IEEE1394 setup, you will be able to get good "photos" from the video.
Be wary of
digital zoom!! It's all well and good being able to zoom up to 200 or more times, but the shake will be terrible and the picture blurred/pixelated. I usually have it disabled, to prevent going too far. 10x optical zoom is usually sufficient for me. A tripod is a must in this case, and an "ought to have" anyway. Any one will do, as the socket is universal for still/video cameras.
Batteries !! Essential to buy spare(s) of a higher capacity than that which comes with the camera. My Canon came with a small lithium ion one that looks nice and compact, but it only powers for about 45mins without using the LCD. Get larger capacity ones to avoid losing power at the wrong moment!
Another heads-up is about the
battery charger. Maybe nit-picky, but very annoying for me! The Canon arrangement is three pieces : a box like thing to attach the batteries to, a cable to the mains and another to the camera. It has a "fake battery" shape to attach to the camera. Now you can charge 1 or 2 batteries, BUT one after the other and NOT simultaneously. Also, if you are powering the camera from the mains, the batteries will
not recharge until you disconnect the camera powering cable. I hope that makes sense! Therefore you have to wait twice as long to charge up, and that can't happen if you're using the camera. Minor quibble perhaps, but I don't like it.
An IEEE1394 card and cable has been mentioned, and I'd add that it's essential, as the "normal" PC download can make for HUGE files for even a small video clip. Another heads-up...don't buy an incompatible card thinking software will make it work. I did that with a Pinnacle Studio DV (NTSC) from Canada, assuming that I could just use the European drivers to make it work. Alas, it doesn't, so my 70% saving is now an ornament! Stupid thing to do

I'm planning to have another go, but with PAL this time hehe, and I have seen good things about the ADS Pyro card. As with the Camera, there's plenty of choice, so search, read reviews and tailor your budget etc.
Whatever you go for will give excellent results, hope this is some help.
Cheers.