Your idea of composing parodies is great.
When you write for other artists - you have to "tailor make" a song to suit them 100% - So copying their style and chords is a great help.
I've always done that.
I currently have a hit song in the stage musical "Dreamboats and Petticoats" and if you listen to it ( Crying Time Again - by Bobby And the Conquests) the song is very similar to most of Buddy Holly's songs.
This was not a rip off - but a clever way of writing in his style - which is what the producer of the musical wanted.
This song has earned us over £15,000 since it came out on CD.
so keep basing your ideas on your favourite acts, then inject some original words and chords.
If you need help on home recording - I can point you in the right direction.
JW
www.songwritersandproducers.com