It is legal for anyone to open carry here. The same rules apply to it as does CC, you cannot have it on any school property, on any government property, inside or on the property of any daycare, or in parks.
If it's listed on the door that no weapons are allowed, don't go inside. The signs don't carry the weight of the law but you will be starting shit and ti won't turn out well for you. While it is okay to carry downtown, there is a good chance you will be creating joinder with metro as there is no shortage of retarded tourists there who will call the cops because "OMG he's got a guununnn!". I have open carried inside a casino before. As long as you look respectable and are not on the gaming floor gambling they typically wont hassle you. Unless a retard makes a scene then they will politely ask you to leave. If you don't, they will politely throw your ass out the back door. Some, not all of the casinos have no firearms signs posted, be mindful to look thoroughly.