Somethings cannot be hit by non-magical weapons. Some, more powerful creatures can only be hit with +2 or better weapons. Some, even more powerful creatures (such as Iron Golems) can only be hit by +3 or better weapons!
Yell works best against spell casters, as it directly affects more intelligent creatures. It will do almost nothing to undead.
2/3 of your party is elves? Well, I hope you get lucky and don't find the end of throtl with all the hold person spells :P
A target affected by any form of paralysis will die if it gets struck by a melee attack. Lots of creatures can paralyze your party members, with spells, poisons and other such things. Don't lose the dwarf, as they are nicely resistant to poisons. However, ditching one of them elves for a kender might not be a bad idea...
Also, a kiri-jolith cleric thief may Start with better thaco, due to the +1 bonus, but cleric/thief thaco over levels is much slower than a fighter thief. Also, the hps of a cleric will always be less than a fighter, because they roll a lower sided die for hps.
If you already have 3 other clerics, you are more than well equipped to lose 1. Also, you have plenty of spell caster power in your party (White mages, red mages, and yes, even rangers) But you want Half-elves, not Qualanesti or Silvanesti. Those two just are impossible to bring back from the dead. Thats really annoying when even on easiest difficulty your level 7 elf just keeps dieing no matter what you do, right before the final pair boss. Besides, I think dwarves make great rangers
