Interesting. Usually people only ask if you could pick 1 superpower, so I’d never thought about 3 of them. With 3 to choose you get a lot more flexibility :D
1. Teleportation. Better than flying, since you can get somewhere instantly. Plus, with teleportation, you are not limited by distance, gravity, or any of that nonsense. If you want to have brunch on the Moon, go for it.
2. Density Control. Basically, to be able to make yourself more dense (even harder than a diamond) or less dense (intangible - walk through walls). This is as good as invulnerability at either extreme, plus you get other benefits too. Also, this is kind of essential if you are teleporting into a place you are unfamiliar with, just in case you teleport yourself inside a wall, or a volcano or something.
3. Matter Creation/Transformation. So you could make anything you can imagine appear out of thin air. Not only could you say, create a pile of gold to finance your adventures, but you could make all sorts of crazy gadgets, or a supercool lair to hang out in. This would also be handy, in case you teleport yourself underwater or something, and you wish you had some scuba gear!
As for what I would do with them, that is a trickier question in my opinion. The temptation to flaunt the law and do as you please would be pretty great, but I think I would probably just set up with a nice big island fortress and set up all sorts of nasty defense systems to keep out any unauthorized intruders. After that, I would invite FReepers and other sensible folks to come populate this island of sanity and write their own constitution (hopefully a bit more explicit this time).
Once all that was taken care of, I would probably while away my time teleporting around the world pulling pranks on commie policitians and tyrants while they were on camera, to make buffoons out of them in front of their subjects.
LOL!
You have a vivid imagination!
I like your reasoning. With 3, there are unlimited combinations. I never was asked that type of question before.