[Aerich]

Which traps? If you're talking about the ones at the entrance that trigger a bunch of skeleton warriors, you can't detect those. You just have to send one character in to trigger them, then run back to the doorway to make your stand.

In this game, it doesn't pay to advance your party all at once. Always send a scout. 50% is definitely enough for that stage of the game.

I'm not a big fan of doubling up character types. I try to have my characters serve different roles (e.g. primary fighter, secondary fighter, or mage, etc). I'd rather have a ranger + paladin than 2 rangers. Two illusionist/thiefs is a waste of XP and character/party potential. Have one multiclassed thief. Fighter/druids are one of the better combos to double up on, but it's also nice to get the party-buffing spells of a cleric.

One of my favourite parties is:
Pally
R/Cl
F/M
F/D
F/T
Bard

It pretty much covers everything, and is very strong with missiles and melee, in addition to magic. It's better for a high-xp game (e.g. on Hard or Insane difficulty level). On a normal game, you may wish to make one or more of the above characters single classed (but not the thief).