The standard indexer will work for straight or either helical. As I understand it, the L and R indexers were developed to give compounders better fletch/cable clearance. There isn't much difference between them and the standard indexers and we got along just fine before it became an issue. That said, the Left indexer does clock the fletching a little nicer than the standard and I suspect the Right does the same.
I've tried the BW 12 o'clock cock feather thing and it does work well; similar to shooting cock feather in. Most shooters still prefer the regular cock feather out, tho. Old habits, I think.