Pick N roll or Moving Screen

[rwest]

I completed my first season of officiating basketball this past November. So, I'm still a rookie. I don't have my rule book with me, but I recall that a blind screen is illegal if there is not at least one step between the screener and screenee. This gives the screenee a chance to avoid the screen. How often do you call this and what do you have to see as far as contact/displacement in order to call the foul? Also, what is the correct call? A block? Push?

How about when the screener doesn't keep his elbows tucked into his/her body? Suppose the elbows are out passed the hips? What must you see to call this? Displacement or just the fact that the defender had to swing out more to avoid the screen?

Thanks!
Randall