16:9
Can I suggest that you check out the Sony PD150A, which I'm fairly sure does true anamorphic 16:9. (Don't quote me on this, check for yourself)
Panasonic also has a new camera in the same price rance which also has a 16:9 setting, but I'm not convinced that it's true 16:9. it does however have progressive scan, which makes for a much more filmic image.
You can convert 4:3 into 16:9 in post, but only by cropping the image. This would make framing during the shoot a real pain in the butt, as you'd have no way of really gauging your frame edges. if you do this you are going to loose some of you image, meaning you'll need the best possible mini DV picture you can get. I'd probably suggest DV Cam, rather than mini DV for this. Again the Sony PD150A.
If you check out the Sony, Panasonic and JVC websites you should be able to get specs on all their bottom end broadcast cameras.
The Sony PD150A is a very common ENG camera in the uk. JVC do some interesting bottom end full DV cameras, designed for studio and corporate work. they aren't much more in price than the top end Mini DV cameras. I would be fairly convinced that they'd be switchable between 16:9 and 4:3.