1969GTOJudge Battery shouldn't matter too much, the servo operates off of the voltage sent to the receiver, which is always regulated by the ESC. If you know that you are getting proper voltage to the receiver, then the servo may have a defect. The servo isn't very fast, but should definitely have plenty of torque.

1969GTOJudge The batteries do not matter, the receiver gets a standard current of 5V (BEC) from the ESC no matter what batteries you use

1969GTOJudge It's perfect for night driving, it is super bright, I have one on my Slash Raptor and it's awesome. I can not only see where it is, but yes, also see what it in front of the truck. And, you may or may not need to know, it takes abuse very well, my Raptor does not like to stay planted on the asphalt, so it rolls sometimes, and the light bar is mounted on the very top so it gets the worst of it, it works perfect and nothing has broken, I doubt it will. As one would assume, all that has happened is that some of the black anodization has been scratched off, and there is the odd gouge, but I just cover it up with a sharpie and everything is fine.

BG131714155 Yes, it comes with a few. At least one round and one four sided horn. Nothing too heavy duty or fancy though. I slapped this in my Stampede and it has no problem turning the wheels, so I do highly suggest it.

BG131714155 The 3rd wire (the white wire) is a signal wire, in this case it has no use. So all you need to do is, as you said, apply voltage to red and black. Essentially, you can just plug it in to an extra channel on your car or truck (even one without a radio switch).

BG131714155 Ido not exactly know, but since the length of the light bar is 5.7 inches, that would mean your roof should probably be at least 6 inches wide. You could turn the brackets inward if your roof is only 6 inches wide. I had to do this for my Traxxas Raptor and it fit perfectly.