If the iris were planted last year, they probably don't need dividing yet - every three years or so is probably fine. If they're prolific growers and look crowded after bloom season this year, you might consider dividing them then, but dividing them now could jeopardize this spring's bloom.

Iris don't need a lot of feeding - two or three times a year is fine. Feed about six weeks before bloom time (which is mid-April in your area, so feed around the beginning of March). Feed again after bloom is over. Use a balanced fertilizer (10-10-10 or equivalent) or bulb food - the thing you want to avoid is high-nitrogen fertilizer, which will give you lots of leaves but few blooms.

Enjoy!