I have the stock AirRide lines, compressor and sensors still in place. I wouldn't use the old lines to fill the bags, I'd use the Aux line coming from my stock compressor, until I could replace that as well. I left all the stock components in there so I could run the new lines in the same place.
As far as the difference in ride quality, I guess that depends on how you use it. The AirRide was kinda bouncy at times. Like a rear tire dropping down off something would bounce. The more weight you hauled around, the bouncier it was. It was nice and smooth on the road though, and handled the smaller bumps better. The Z71s are a little more harsh on the road, but seem to get a little smoother with weight in the back. Great for loaded up camping/hunting trips. You get used to it either way...