I'm sure you'll get the standard replies about stuff you already listed.
I will add that you should learn at what position the wind hits the top of your helmet where the top of the visor meets the helmet. This is useful because in the rain, your visor will get wet on outside (obviously) but it will most likely get wet on the inside (when you open the visor to defog). I found that if you open your visor (assuming full-face helmet) to the first click and position your head into the wind stream where air can enter the top of the helmet, the water will be forced down and automatically defog the inside of the visor. You will see drops stream downward -- I call this "defrost" mode

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Depending on your windshield, I think you can stick your head out from behind it (at speed) and the wind will blast/clear the water off the outside of the helmet.
A little rubber strip on your left glove finger is nice and can act as a windshield wiper; I move my finger across my visor in the motion of a windshield wiper to entertain the drivers around me

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With my Road Smart tires, I went close to 85mph (GPS speed) straight line in the rain -- ok maybe 80mph -- but still the bike felt very planted. I still kept things close to vertical on turns. My point is good rain tires help in straights but I'm still not sure on turns.
Avoid following cars because the rain they spit up is worse than the rain itself for visibility.
I keep a set of velcro (bright yellow) strips with me and if it's raining, I put them on my wrists for added visibility. If I'm in traffic, I will periodically tap my brake so my light will flash. I want to provide something flashing to alert drivers of my presence.
I rode through a torrential downpour one time; I realized that my bike did not have pariscope and so was probably not a submarine

so I pulled over after about .25 miles and sat it out for about 20 minutes until it was just rain.
Practice riding in the rain so that any apprehension is reduced and you can concentrate on being safe. Some of my best rides have been in rain.
Dennis