In response to your first questions see
F.H.C. Crick, L. Bartnett, S. Brenner, and R.J. Watts-Tobin. 1961.
General Nature of the Genetic Code for Proteins. Nature 192:1227-1232
F.H.C.Crick 1966 Codon-Anticodon Pairing: The Wobble Hypothesis. J. Mol.
Many people are given credit for cracking code words. But this will give
you a start at least. Good luck..
rcjohnsen at aol.com