Some novice questions

Hi. I'm completely new to OpenAL and I have some questions:

1. what value ranges do all the float buffers take?
2. when I play with source position and listener position, I see a difference only when changing the X axis (left - right speaker) but the Y and Z don't work. I use a mono sample. Is there any switch to enable this??
3. the source velocity - does it impact anyhow the sample played, or is it just for me to take it's values and manually change the position? I mean, does the AL compute something using the velocity?

Cheers!