Don't know the problem with the composite line -- should be the same from Winamp Plugin as in their software -- in fact Hauppauge has links to the SAME winamp tv plugin in their own website.
The reason why SVIDEO is black and white for is is that the wintv is probably set to NTSC while you're feeding a PAL-M signal.
The reason why you can't tune channels is FOR SURE that the signal is just not good with your current antenna. WinTV cards have very poor reception on my standards..
I myself would never use any software for rearview, I'd just plug it into the monitor's composite in and whenever needed it'd be ready with a press of one button always on the monitor.