I am currently contemplating about an AA build and I am nor sure if I want a pure Ranger AA or a Monsterish build (http://forums.ddo.com/showthread.php?t=278181).
The main difference of the two builds is against whom they do damage. While a pure Ranger excels against FEs (+14 Damage against those), a more Fighter based build will deliver good damage against all Mobs.

The canonical choice of FEs is Undead, Giant, Construct, Evil Outsider and Elemental.

1. When will I meet Mobs which are not from this list?

2. If I do fight non-FE monsters, is the lack of DPS noticable?