IwubCheeze: Like I said, it can be hard to pinpoint whats going wrong when we can't see exactly what you're doing. Does anything I mentioned above sound like it could be the source of your troubles?
glunders: Thanks. I think I went wrong with weapon proficiencies—I have a ton of slashing/piercing but next to no blunt weapons. (Cleric is pretty much the only one.) I have been using bless and not turn undead, but yeah, I think I'm having problems in large part due to my weaponry not being optimized.
My mage/thief is also just horribly useless. (In retrospect, I don't really know why I rolled this.) I can replace her mid-game, right? I wonder if doing so with a character proficient in blunt weapons could be helpful. Might have to grind out some fights by repeatedly resting in unsafe territory--does that work?
Glad we found the problem :). In this game you definately want blunt weapon damage, it can handle any enemy in the game except for the 5 or so shamblers in TOTLM (they are totally immune to blunt damage).
Except for your thief / mage (definately replace this one), your characters have 4 proficiency points to spend on character creation. What I do is drop 2 into a ranged weapon right off the bat. Low level characters are too squishy to handle much toe to toe combat. After that, I put 1 in a blunt damage weapon and the last in another damage type. This gives me a balanced weapon loadout with emphasis on ranged weapons for higher low level survivability. I then increase the other two as I level up. For single class fighters, I do the same thing until they have two points each in a missile / blunt / other damage type, then I max their ranged weapons (3 for bows/xbows, 5 for slings) then max their main melee weapon, the rest of the points go in the other weapon.
Just a few tips on choosing weapons, be careful about taking quarterstaff proficiency as there are barely any good staves in the game, in fact, the staff Conlan sells will be the best one. In the original game, you will probably only be able to find two, one only a druid can use, the other only a cleric can use. If you have a fighter with quarterstaff proficiency and you don't buy the staff from Conlan, they'll be carrying that piece of firewood well into the TOTLM areas and it will be for a quarterstaff +1, lame!!!!!! Halberds have the same problem, one of my fighters wth halbard proficeincy kept his ordinary halberd the he got in Easthaven until he met the blind dwarf in the HOW areas. Before there, you have a chance at finding 2 halberds but they are both random drops, one was in Kresslacks tombs in a small room containing a mummy, in that room, you have a chance at getting a diseased halberd, I forget there the second was could be found though. Clubs are also a problem, the spidercrusher from Conlan will be the only club you find until you start HOW where some great clubs come available.
Yup, you can replace characters mid game and you can always use the cheat console to bring their XP up to par with your party so no problems there. The fighter multiclasses are great choices for characters because of the higher hitpoints and better weapon proficiencies over their single classes counterparts. To me, sacrifing a few thieving skill points or a few spells for better combat viability is a good trade off. May I also suggest taking a ranger/cleric instead of a fighter/cleric? At higher levels, they get both cleric and druid spells (except for level 7 druid spells). :). IMO. ranger/clerics make fighter/clerics redundant. The only thing a fighter/cleric has over the ranger/cleric
is more alignment choices which really only amounts to a few crappy cleric spells. The cause X wounds spells are garbage anyway. Long spell casting time, crappy damage and a chance of a saving throw makes those spells useless, using the spell slot for a buff and swinging your mace instead is far more effective.