Yes, what looks like a chair lift is the long zip line. They have two zip lines at Labadee. A short one near the pier and then the long one where you go to the top of the mountain. What they did was have you do the short run first, then you were qualified for the long run. It gets up to 50 mph! Dragon's Breath is the area just inside the entrance at the end of the dock. In the photos you see a couple buildings at the end of the pier. The one on the left (if you look at a photo taken from the ship) is the security station where they have the x-ray machines.
Labadee has had the x-ray machines on land for a while now. I remember using them in 2006, maybe even earlier. This was to facilitate things for the Voyager and Freedom class ships given the tendering would cause log jams at the ship's entrances.
RCI had set up security lanes on the pier in St. Thomas and St. Maarten for the Oasis, but given the ship sailed half full this week they won't be stressed to handle the crowd.
I've done the zip line in Labadee. It's quite fun, but like Dave said, a little jarring at the end so if you have back or neck problems you should forgo.
I wish I'd gotten a copy of the release I had to sign before I went on it. It's quite detailed as to what can happen to you.
There is also a weight limit. The day I was there a man who had signed up for it was not allowed to do it because he was over the weight limit. I think combined with the wind it was a problem. Maybe if the wind had been different he would have been able to go.