The sound produced by ANC is the exact 180 degree inverse (or as near as possible) of the incoming bad noise.
It's produced in realtime by dedicated signal processors and requires mic arrays feeding in the sound. The quicker your processing pipeline the better the match is and the more powerful the effect is.
There's no prerecorded sound that would work.
Yes. On older generation/cheaper ANC this is perceived as increased "pressure". It doesn't seem louder but the physical sensation of loudness is there.