Congrats on the new bike(s) Kelly. Sounds like you’re in for lots of fun.
In response to your “issues”:
Signals: just keep working at it. You’re probably a bit overloaded by all the new controls. Don’t lose control of braking for the sake of signalling, but keep working it in and before you know it, it will be automatic. Also, a bit of driveway practice cycling your hands through all the controls can help create musle memory and ensure you’re never looking down to hit that right-turn button.
Shifting: as others have said, you can count up/down, or use some type of reference to speed (though different bike models will be in different gears. I don’t typically do either, but rather match the engine revs to the speed I’m currently. If I’m slowing for a turn, I’m sliding down into lower gears, releasing the clutch with each gear (typically without high revs). This allows me to always have the bike in a gear that allows full control and also avoids ever being in a situation where the gearing is out of sync with the current speed. When shifting up, I shift when I went to reduce revs. I don’t really care what gear I’m in — if the revs are right, I’m in the right gear. If I’m accelerating, the revs eventually get higher than I want and so I shift.
Tailgating: sucks, but I don’t typically have it happen very often. One thing I’ve found that works is to make the driver pay attention to you and recognize that there is a human on the bike. This may be as simple as waving “hi” at a passing car (who cares if you know them), sitting up straighter and putting your left hand on your hip, standing up on the pegs and stretching for a few seconds, moving around a bit in the lane, etc… (Please keep in mind that these should only be executed if it can be done safely.) If that doesn’t work, it might be better to pull over and let the a—ole go by.
Overshooting the bank: That’s a scary one. Basically, you’re saying that you were out of control and unable to ride the bike in the intended direction. If you aren’t able to direct the bike to go where you know ahead of time that you want to go, how much worse will it be when you need to ride it in a direction dictated by unforeseen circumstance. This kind of thing has likely happened to all of us, but IMHO, it’s a sign that you are out of control and the bike is basically riding you. Think about what you’re missing (throttle control, proper lane position, ???) and practice to be safe.