can the tops of kohlrabi be eaten? do they need to be cooked?

Kohlrabi greens are really delicious. Often the stem is a bit tough, so cut out the lower part of it. Then slice the greens and braise them in a bit of water with a knob of butter. They have a similar texture to collards.

Certainly. Taste them to determine if good raw--if freshly cut, they would be fine, but larger leaves may be too tough.

Yes, my grandmother always cooked them. I think she steamed them first and then added them to a cream sauce.