I would recommend just running a Wizard as both your Wizard and Rogue. Wizards are capable of investing skill points into the disable trap skill, and although their maximum skill rank is much lower than rogues their intelligence score adds a bonus to this so they remain competitive with Rogues right up to the end of the game. I ran through my IWD2 playthrough without a Rogue and my Wizard was able to disarm every trap I came across (there were a few he struggled with, but nothing he was unable to disarm with a sufficient number of tries). I'd recommend not running a Rogue at all; it's very weak in combat and not worth running in your party.
Don't multiclass Monk/Rogue. The two classes have no synergy and compound each others' biggest weakness (poor attack). If you're going to include a Monk, stick with single-class. And make sure you max out strength; this is always important for melee-oriented characters, but Monks have less margin for error than other classes.
One last aside: make sure your Cleric/Paladin takes only a single level of Paladin. All the good stuff is gained at 1st level, and Cleric is strictly better afterwards (paladin gets slightly better attack progression, but Cleric gets vastly better spellcasting. It isn't an even comparison at all)
