monk as tank? - 1. ioun stones vs criticals; 2. dual wielding

Basically, can the Ioun stones block critical hits in BG2EE? (Otherwise a monk has x2 damage vulnerability even with the best AC.)

Also, can it gain +++ in dual wielding?

If yes to both, a monk dual wielding katanas in the frontline with magic resistance boosting items seems to be a formidable opponent and a much better wizard slayer than the wizard slayer, no?