This question belongs in the Expanded Universe Forum
but seeing as I would be the one answering the question over there, I might as well answer it here
here is the CUSWE reference for Plo Koon.
It will give you a detailed account of Plo Koons actions as depicted in EU until his death in ROTS. In addition it provides specific references where this information was take from. I really cannot recall fiction/comics dedicated to him specifically. He has appeared in some comics, as listed there as various WOTC/Insider stories. He was also a playable character in "Jedi Power Battles" for the PSOne.
There really isnt much more to add, actually