For #2 - you can swap freehub bodies on Campy hubs between EXA and pre-EXA. The thing is the axles are different for the two generations, but the hub shells aren't. There's a step in the axle where the freehub sits that's a little shorter on one than the other. So if you have the wheel built and a spare hub from different generations, take the freehub and axle from one and swap it with the freehub and axle from the other. Then an 8s Campy EXA-drive cassette should go onto your new wheel.