Heh, I have never played with an Isengard list but it is one of the main armies I have played against it (a lot) and as such i can see some flaws.
Firstly, you seriously need some crossbows.... cause if you don´t then the enemy has the "home field advantage" as he will just sit back and volley...
Secondly replace the Uruk captain with a named one, Vrasku or Ugluk in that case as they have basically the same stats line, but with an extra special rule and a point of might. Your list will still be fully legally allied cause Shaman can be the used for this.
Thirdly although this is quite optional, You could add a banner bearer, as you will likely be outnumbered thus having a re-roll with a higher fighting skill is nothing to be over looked. But banner is actually a matter of personal taste.
But over all a nice, fun looking/playable list. I like it
About the elves...
Again max out the bows...
With that list you could get 9 wood elves with bows...
And im not so sure if you should buy your elves elb blades, cause most of the times you are outnumbered , meaning you woun´t have anyone in the fight to add the regular fighting rolls.... It´s worth considering adding them elf spears....