A lot of the reason we cannot get old world species in the US is because of the risk of escapees. The US Fish and Game does not want to have to deal with an import quail pushing out the native populations, they have enough problems with this already.
Quail (or really any bird for that matter) will be more friendly and tolerant the more they are handled, and the earlier you start. While they many not imprint the same way a duck might (we could go on for hours about avian psychology, but it is too early in the morning for that), but more they...