Acronym Soup: ITAK?

Questions

- Spanish stage entertainment involving a few singers.?

- In a fugue, for example, after the first entry has been stated there is an answer (or second statement at a different pitch). If this answer is slightly modified to keep the music within a certain key, then this is a tonal answer and the fugue a tonal fugue. This is the opposite of real answer.?

- Observance of a single key. Atonality, lack of key. Polytonality, the simultaneous use of several keys.?

- (1) The interval consisting of two semitones (e.g. C to D); (2) The quality of sound of an instrument.?

- A 20th century concept of playing an adjacent group of notes on a piano simultaneously by applying the forearm, fist or piece of wood to the keyboard.?