Actually, doctor told me that my donor area is massive with a great potential, even though I opted for a mature hairline (I am 28). I did not want an unnatural 20 year old girly hairline which most guys look for (I want more like Don Draper hairline). Also, I have thick wavy hair, so it covers bald spots well. Maybe, in the future I will do another one, It depends on the results.
About the gap - I had chickenpox 3 months ago, and fungus afterwards, so It might have lost a bit of a density in that area, because when I magnified the image I saw the grafts in that area.
Tbh, I don't know the exact amount of grafts, It could be more than 1000, because I didn't ask to lower my hairline (although after their recommendation I accepted it). The surgery took around 6-7 hours, so they could have placed more grafts.