Thanks for the replies and sorry it's taken so long.
Damn, just wrote out a long reply and lost it all

The Carn Dum contingement is my favourite part of the Angmar force, just because it's not something everyone does. If the Dunlending models weren't such a nice fit to my mental image I'd give in and make a list based on the Warriors of Carn Dum using the AotD plastics. The option is still highly tempting.
Anyway, I don't believe the bows hurt that much. Particularly as it's only 3. I still have the numbers to volley (with the replacement 24 Orcs). Granted, if I take a few casualties then I won't be able to, but volleying only generally works for the first turn or two before the range is too close, after which the better shoot value actually helps.
And the problem with cavalry is that you have to go big or go home. Adding in say 6 Warg Riders (forgetting the problems of allying them) is almost a worse situation, as it's enough of a threat to attract attention but not enough to protect the WK. Then if I go more, I'd want a might hero to help dictate the charges, which is not a position I want the WK in. And suddenly I've got a major cost in points/money and the force composition is nothing the same. I'm hoping that by keeping the WK without support that he'll avoid the enemy's focus while there are closer threats and that I'll be able to use models/terrain to hide behind to make the effort spent trying to shoot his horse down beneficial to me even if he suceeds.
As for Fenrir and the Goblins...
The extra courage can only help I figure? More importantly though, it saps the opponent's courage and provides a banner to my hordes. If I can get that into a key position, it may help a little. I figure I may as well test it seeing as I have the model. Even if it isn't that effective, you gotta admit it's a very characteristic part of the force.
Wild Wargs/Giant Spiders is something I've been considering. Depending on whether I make the points to buy enough for them to be worthwhile. No point charging alone into the enemy, and once the main line arrives, the goblins are capable of swarming the enemy.
And I don't know if I will have the 2 trolls. A few posts up, I mentioned that I might try removing the second troll for an extra 17 warriors.
At the moment, I'm liking the second list, because I'm busting to try something with a big monster in it. And trying to resist buying a Fell Beast and starting a Mordor force.