Questions about SAW filter design

hey all,

i'm working on the design of a 35-45 MHz SAW filter on a 500mm, 36degrees Y-cut, lithium niobate substrate.
Q1) Is it important how do i place the fingers on the substrate? I mean, does the direction on the substrate differ?
Q2) I have some idea about the x-axis which is finger width (lambda/4) and finger length (lambda)
how about the y-axis; width of the transducer ? what does it effect
Q3) Do you know any tools for simulating SAW filters?

Thanks.