You'll know right away if you break the tube. It will make a sickening *tink*PSSSSSSSSSSSSSSSSSSSSSssssssssssssssssssssssss as your heart sinks knowing that tube is destroyed. The glass exhaust pip is fragile so you do have to be careful unplugging that connector. Once air has got in the tube, it's a goner. It could be rebuilt, but to my knowledge there is only one remaining CRT rebuilder in the world, RACS in France and obviously that is not cost effective for a tube like this.

There is actually very little shock hazard working with these small tubes. The high voltage is at the second anode, the connection under the suction cup looking thing. If you plan to work around the tube, it is a good idea to discharge this, but if you are expecting a big flash and bang you will be disappointed. Connect a wire to the bare ground wire sprung around the bell of the tube and poke the bare end under the suction cup. If there is any charge left, you may get a small spark like static electricity on a dry day. I usually clip an alligator clip between the anode connection and ground to keep it discharged, sometimes a bit of static can build back up from inside the tube. It won't kill you but it could startle you enough to drop the tube on the floor.