1: I couldn't get the bullets to pass through anywhere, so I don't know what you mean.
2: Your character's max speed is greater than the speed of the bullet, you should either speed up the bullet or slow down the character. You would run past bullets in real life as well, if you were faster than them.
3: Instead of using the ScrollTo behaviour, use the system actions "Scroll to position" and "Scroll to X/Y". To limit the scrolling, all you have to do is compare two values and input "ScrollX" or "ScrollY" to get the current scroll position.