Actually that was EPIII and the Visual Dictionary, that included Vader's Fist first.
Thats a slippery slippery topic.
Canon as far as I've ever heard it is tiered, Canon A being what is used the most for 501st Costuming calls, that is anything in the movies or things offically eleveated to the tier by LFL, so far there is the following that they call canon- The Force Unleased, the Clone Wars movie and the currently CG Cartoon series.
Canon B is the offically sanctioned stuff, this is where Battlefront, all the EU etc falls.
Canon C is fan fic and alternate universe stories like "What If?" Styled comics from a few years ago of the original trilogy.
The heavy weapons trooper is accepted EU variant of TK armor, that is where you can have a TK with pauldron.
As far as an offical ranking? Other than the pauldron semi-ranks that I think hasbro did a number of years ago, there is no offical one, and I have heard the ear stripes where a rank system but I've never seen nor heard of a rank system guide applied to them.
Wear the uniform, have fun. If your at a non-canon event toss on your pauldron, if your not, and your not, don't.