I have already done it there. So you can imagine what that means. When I bike in Portugal I dress colourful and bright clothes so that I can be spotted from a long distance Police totally ignore bikers, I would say that they view them as pedestrians. So you won't get bored by a policeman. Other than that nothing else is required.
All roads are extremely unsafe.
Portuguese are almost the worst drivers in the world. Never believe that you are safe on a road in Portugal. Even if there is less trafic, people will then drive more carelessly and faster. Unless you drive at night, you are not required to have any special equipment in your bikes. Buy a good health insurance before going.