Hi there Mo,
Sounds like you're interested in portrait photography. What fun!
My skills lie more in the realm of natural history/wildlife photography but I'll try to help.
Since lighting will be of concern to you (both high key and low key), I'd look for a camera that you can have manual control over. You'll want to match your combined lighting rating then be able to set your camera to the same aperture so you'll want to be able to select your aperture manually. If you need to make adjustments to overexpose your shot (for high key for instance), then you'll also want your camera's metering to include spot metering and you'll want to be able to adjust your EV setting.
To flatter your subject's features you'll probably be some distance from them (ex. 10-15 feet) and so will want a portrait lens (typically 85-135mm long). This allows you to fill the frame with their face while diminishing the closeness of their nose relative to the rest of their face. Manual focus might also be a plus.
Regarding color, you'll want to have control over the camera's saturation settings. You may also find that you have a specific preference that you'd like to use most of the time and it would be nice to be able to define that as a preset. Some cameras come with "user defined" preset banks.
If you're going to be doing B&W rather than color, then you'll still shoot in color but convert it to B&W in post production.
You mentioned wanting to produce 11x14 prints. In that case I'd opt for a 6mp camera and shoot in RAW or TIFF mode. You'll want the extra megapixels in case you find you have to crop your images.
Also, I go to a professional photo shop in your area and ask them about specific camera models best suited for portrait photography. I bet they can give you some good ideas and you can get a fee for the cameras you like.
Hope this helps to get you started.
