Not sure about conures but we adopted amazon and a african brown head.
The brown head tends to be nippy when she doesn't get her way. I will only take her off my partners shoulder or from a cage with a stick, she is generally good except for those times.
Our Amazon was really excited in the beginning which made him nip harder than he does now, but it wasn't a bite mind you.
The best way to not get bitten is to avoid the bite, the excitement should wear off after owning him a little while. Also we try to follow the rule that the bird shouldn't be up on our shoulder until we trust them and they must come off when asked.
Regurgitation is a sign of love, ours did this as well.
Good Luck