Well...
Right hand is the main hand. Main hand attacks can cause double attack (unless crit occurs), and cards from both hands apply on this hit. Left is offhand, and serves just as card carrier.
Using IP and CK together is NOT recommended, as CK effect would negate IP effect.
And dagger builds are NOT crit based. Usually, for crit builds katars are used because they double the crit rate, so when you reach 50 crit is status window, it is actually 100 crit.