That person had help from contractors and heavy equipement. It's part of a CCP escapist propaganda initiative.
And to answer your 2nd question, not all rocks are the same. Some are highly friable and could be worked with a hand saw. It's how the Euros managed to make such awesome cathedrals and shit. If you are ever near one, you could basically embed your car key in the rock with little effort (pls don't though).