As for the skills for your players, I'm a huge fan of putting points into bow skills and armor skills first. If you can inflict damage from farhter away, that is a huge help, especially since you have some characters that aren't going to do huge damage close up.

FOr your knight, I agree with sword, bow and plate. The only question is, whether it is worthwhile to develop shield. IMHO, the added damage points from the second sword doesn't outweigh the shield benefit, especially if you get one of the better artifact shields from the Titans stronghold. If you are fighting creatures with deadly attacks,m it might be better to have greater defense. On the other hand, if youknock up your sword level, you can get rid of them more quickly.

As for the cleric, definitely ramp up your mace skills. You can still do some pretty good damage later in the game, again with a good mace artifact or magic weapon. YOu might want to think about raising your sorcerer's magic level and letting him enchant a quality mace. I saved a rgame with a regular mace and used enchant item, reloading until I hit the jackpot for my cleric.

I haven't gone with a druid yet, so can't help you there. The GM alchemy isn't worth it to me, since you can buy black potions by the time you would reach GM in alchemy anyway.

Good luck.