It is my understanding that Flashing lights are illegal. Only service vehicles (police, ambulance, fire) are allowed flashing lights.
There is a benz that flashes its brake lights when you really stomp on the brakes to warn people behind you – proven very effective BUT merc had to apply for a special permit to trial these cars in the US.
Do not run your high beams during the day, yes they are brighter, but they are also aimed right at the eyes of other drivers. It WILL piss them off, and it may cause on coming traffic to focus on you (and thus drive towards you). Don’t think it’ll annoy/blind drivers, ask your MSF instructor what it is like teaching a class where someone uses high beams. They didn’t have kind words for the guy who kept blinding them with his high beams in my ERC course.
You want to be bright and visible? Wear a high visibility jacket or vest. Period. Nothing will get you seen better in any condition than a high vis yellow jacket. Are they cool looking? Not really (though I did see some BMW ones that looked good, and the dealership sold through 50 of them in a week because of it).
“The two seconds between ‘Oh S**!’ and the crash isn’t a lot of practice time.”