It is legal to open carry. I would not do it in New Orleans. The NOPD is less than happy with civilians being armed. Most of them do not know the law. As far as prohibited places you can not open carry in any place that sells alcohol. The law that would concern open carry with alcohol is http://www.legis.state.la.us/lss/lss.asp?doc=78744
That is the possesion of a firearm law. The newer concealed carry laws sort of contradict this law but since you would OC it would not apply anyway.
The NOPD will stop and talk to you. They may even ask for a bill of sale or some other way to prove the gun is yours. While you do not need to have this under the law they don't seem to care. After they were told that they could not just take peoples guns they responded by saying that people would have to prove the weapon is theirs.
There is no gun registration in LA, and person to person sales require no paperwork. They are just looking for a way to take your weapon. They still have a big humid room with peoples weapons sitting and rusting away.