Never saw this erratic behavior.
The whole idea behind the SE was that you can fly low, and thus undetected, and still could hit your target without fragging yourself. So yes, fast (450-500kts) and low (200-500ft) is the way to go - or a shallow dive.
As you can see in my example this works well. Target was an SA-6, with an SA-15 and some Shilkas as close in Defense.
Not sure if I understand your last question.