If you're in zone 5, or anywhere in OH for that matter, Callas are not winter hardy. What I do is wait for the frost to knock the leaves down then lift the tuber(s) and store in the basement. I plant in spring after last frost. If potted in part shade, morning sun is best. If in ground, 8" deep with 2" of mulch to keep the roots cool. They also like lots of water.

Yes the blooms can be cut off after the spathe (petal) turns green. This will help the plants vigour.

Oh, forgot to mention most do well in full sun or part sun when planted in ground.