Prius C / Aqua: General Questions

Hey all,

So, I've had a 2015 Aqua for nearly a month now. I've given it its first fill-up last week (I calculated that it gave me 21 km/l (49 mpg) for the first tank), and I'm done with most of the trips to the mechanic until April (barring any horrible, terrible accidents, God forbid). I've also had it raised slightly (yes, I know, but with how high the speed-breakers are, and how often the bottom was scraping when I drove over them, I had to).

I'm now concentrating on driving it, getting used to its foibles, and keeping it from getting its first scratch on our notoriously dangerous roads (though possibly not as dangerous as either of our neighbours'). And there are a bunch of questions I've had, seeing as I've come from a manual car, which had no traction control, no "power" options, and certainly no hybrid system.

1. B-Mode. I know how it works, and I know when to use it. My problem is, can I just shift between "D" and "B" while moving? I remember reading somewhere that you shouldn't switch gears on an automatic (and especially not on a CVT) while the car is moving, but then, "B" and "D" are both forward gears, so I guess it shouldn't damage anything? I don't know.
2. There's a lot of horrible traffic I have to deal with, right? So, what'll happen is, is that the car will switch to EV mode. The next car will move up, and then I have to accelerate to keep up with it, otherwise the guy in the other lane will stick his nose in without even a "by-your-leave". When I do that, the ICE kicks in. And then I'll brake (because the guy ahead has stopped again), and the ICE will turn off, and the car goes back to EV mode. And this'll happen quite a bit at certain points during the commute (not throughout, but there are bottlenecks). Anyway, is that bad, this constant switching between EV and ICE? I'm assuming Toyota must have taken this into account, because surely this sort of traffic is everywhere, but I do not know, should I just accelerate more gently if I'm already in EV, and just use my horn to scare people out of my lane (don't laugh, it does work).
3. A few people on the interwebs seem to think it's better to park a Prius with the HVB with a nearly full-charge on it. Others seem to think it's better to drain it. I... don't really do either. When I've turned off the Expressway, and I'm in the residential area, I tend to go slowly, in EV mode (it's about 1.5 km to my house, and downhill), and I can usually make it without the ICE turning back on, and I'll have 3-4 bars of battery (let's call it 1/3rd full).
   
4. Is it better to have the heater on all of the time, or to turn on the windshield defogger from time to time (which will turn on the A/C)? I don't like heaters and things, so I'd rather not have the heater on, but I'll keep it on if that's a better way of keeping the windshield from fogging up.

 

Oh dude, thanks so much! Y'know, the big things are always in manuals and forums, but little things always trip me up.

It'll take time, I think. The car's still new, so I'm still overthinking things.

 

Double post, I know, but I had a couple of additional questions:

1. I just filled up the car, with two bars left on the gauge. Last time around, I filled it up with one bar remaining, and I got 35 litres (7.7 gallons US). Now, the tank is supposed to be 36 litres (7.9 gallons US), so that got me worried, so this time around, I filled up early. The tank filled up in 26 litres (5.7 gallons US). Is the fuel gauge logarithmic? Did I really have 10 litres of fuel in the tank today?
2. With the other cars, we'll only put in coolant occasionally, we'll usually fill up the radiator with water. Does the Prius C / Aqua have to have coolant? Will something go wrong if I put in water?