OC is mostly uneventful here.
Casinos will be one of the major exceptions. You can expect to be asked to leave most of the resorts. But the public sidewalks downtown (Fremont Street) and on the Strip are fine.
Handguns can always be fully loaded at all times that they are in legal possession. And firearms can be anywhere in your vehicle, concealed or not, as long as not concealed on your actual person. Seats and seatbelts do not count for concealing an openly carried firearm.