>2. I still dunno how to get rid of the pointer under intuition.
>  ClearSprite_ every vbl causes the machine crash or it will just
>    flicker...I just want it to disappear completely for a while...

window 0,0,0,320,512,$1800,"",0,0
*w.l = Peek.l(Addr Window(0))
*wmem.l = ?EmptyPointer

SetPointer_ *w, *wmem, 0,0,1,1

EmtyPointer:
Dcb.w 4,$0

or if you really want no window, try setting the mouseposition outside the
screen every time.