I had my nipples pierced for about 4 years. I took them out before I got pregnant and thought the holes were completly closed up. One side is totally fine like it was never pierced but the other side leaks a lot when I am nursing on the opposite side and every single night. The other side rarely leaks at all. Other than the leaking, no other problems. DS does prefer the side that doesn't leak though.
Re: boob question :P
No, but I have been told that it's an extra hole for the milk to come out of!
This should help
https://www.breastfeedingbasics.com/html/ask/pierced.shtml