Yea the plant does that to close off, keep it's water and stuff in. It's like.. a plant scab. Scissors are fine. Plants are pretty good at regrowing themselves, usually most herbs will keep sending shoots up from the base of the root. You picked some good choices to start off with. The parsley and basil will like moist soil. The oregano, thyme, sage and rosemary all prefer dryer soil, so I'd let it dry out completely before watering again. And I'm gonna stop babbling cause I could go on forever about plants. :D
@Laki- Dill. Our dill grows back every year, we don't save any seeds, and there is always so many 3ft tall dill plants that by mid summer I usually go on a rage ripping up entire plants. xD I'm not a huge fan of dill though, ehehe, I'd just want to use it for our pickling, but my mom puts it on EVERYTHING. Potatos, soups, meats, ugh.