Number one is: Kennen can not be a carry since he can not devastate enemy teams (and by that I mean two shotting their carries), while typical AP carries like Veigar, Annie, Brand... can.
Kennen doesn't need Teleport since he is not the type of champion that should be backdooring.
Taking Lightning Rush before Thundering shuriken does not make sense at ALL, you can't check bushes, you can't harras, you can't last-hit more then one creep, you can't deny enemy exp by not allowing them to reach the creeps... Only thing you can do if you take it before is get to your lane faster but on hight elo pretty much no one will be going into the bushes for first blood (and even if you do you won't do some damage because of it's long cooldown).
Rune choices are fine I can't argue with that, though flat HP quints are not my best choice, item build is ok as well, though easily countered with a little bit of magic resist.
Masteries, there has been a lot of argue about these and it was said that going offense with Kennen is REALLY stupid since you need to WASTE a lot of mastery points on worthless masteries just to get to Havoc, it was also said that if you really don't prefer Defense masteries on Kennen atleast go for the utility tree since there is a LOT of pretty good masteries that will not be wasted such as the cooldown reduction, movement speed and neutral monster buff duration (although you don't take it). Finally almost everyone agreed that the defense tree is by far the best one for Kennen, Magic Resist and Armor are always good to have, additional health works AWESOME, Ardor is one of the best talents in game and the final talent is just great on almost everything (ESPECIALLY if you need to walk into meele range to be able to hit with some spells (lightning rush and ulti).
If you think that Kennen focuses on auto attacking as a way of harrassing in early game then so does Brand and so does Swain and so does Annie and so does Kassadin and so does Malzahar, since all of them have quite long cooldowns in early game... The only moment when Kennen should be auto attacking is to last hit and apply that mark of the storm, if you really need to auto attack the creeps all the time then this isn't a guide for pros, because if you watched the championship (I mean the dreamhack world competition) NO ONE and I mean ABSOLUTELY NO ONE was auto attacking the creeps, they were just last hitting them as it should be done.

like it, good work, nice build