All channels, including VC roms, can be transfered to SD (I didn't see an option for USB, but then again, I didn't have a USB drive to test with) The get stored /private/wii/title/(FOUR DIGIT ALPHANUMERIC CODE)/content.bin
They are wii specific, if you try to transfer any channel to another wii, it gives you an error (this channel can not be copied to this wii).
iND released a copy of f-zero VC, that could apparently work, but I and many others have downloaded to realize, its just the straight channel file, nothing special, and does not work.
I imagine if someone had the patients to collect a single channel from a surplus of people, and compare them all in a hex editor, and compare the differences, the security could be bet, but it doesn't seem that anyone is doing this yet.
The wii shop channel hack can apparently be used to add wii points to your system, and/or download the content for free. This isn't sure to be true, but there are videos floating around of a man who did it. He isn't releasing any information at this time.