The piano sound on Answers uses a combination of the Boesendorfer grand piano from Rockfield, and the Soft Piano instrument from Spitfire Labs. If you are into creating music yourself using computer software, then Spitfire offer free instruments in return for a donation to UNICEF as well as their usual library.
Download the Piano Score to work out Steve's piano composition that Chris wrote the Answers lyrics and melody on top of.
Synthesia is a great game-oriented way to learn to play the piano. It appears to be a real go-to alternative to traditional staff-based notation!