I had a play around with it at home but not live.
Yes, you'll need a lead with a stereo jack plug one end, that splits into two mono cables to go to the two amps. You've basically then got two signal chains, one from each pickup, so could run whatever effects you want on each.
I think most people don't bother because it's a lot of extra kit to carry around for little benefit tbh. It's a novelty that didn't really catch on.
The vintage tone circuit is something completely different. That switches in a different value capacitor to make it sound like the early 4001/4002 basses did - less bottom end, more glorious clank. Modern basses have a deeper bottom end but with the loss of the clankiness. My 4003 is a fairly early one and didn't have the vintage tone circuit from the factory, so I retro-fitted one myself