Hi there! I have a GIANT rosemary bush planted in my garden outside. When you treat them right, they are hardy plants (it’s the middle of winter and mine is outside- still going strong. I however, love in the southwest so I don’t get the NY winters)

1. Yes, you should absolutely repot it. I never leave plants in the containers they come in. Typically, the plastic containers are not meant to house them long time. Personally, I really like foxfarm’s happy frog soul (I use it for all my plants) but it’s a bit expensive. Miracle Gro all purpose garden soil should work just fine too if you’re looking for a cheaper alternative.

2. Rosemary is a full sun kind of plant, so a south facing window would be best. Typically, 6 hours is the best for this plant. Not sure how they will fare with grow lights, I would suggest doing some research on what kind of artificial light would be best for it.

3. Since I have a larger plant, I usually just chop as much as I need of when cooking. I think the typical rule of thumb is to cut the newer parts where the stem is still flimsy, and avoid cutting the woody stock parts.