Overflow and on-the-fly properties

[MrDoubtFire]

Hello,

I am constructing a website for a business, 2 frames with the top frame being menu frame and always static, the lower frame being where information is displayed, purchasing etc.,

On the lower frame I have attempted to present lots of information via <div>'s, to mainly avoid using the window's scrollbar. However on two outer <div>'s I have information that might overflow the displayable portion of the normal <div>. So I set 'overflow: auto' in the style. This style declaration is inline.

My questions are:

-) I have 'overflow: auto' set, but no style for a scrollbar. Should I set scrollbar information for that <div> in an external stylesheet or inline
-) if I do set style for scrollbar, and no scrollbar is required/needed will that cause validation problems? Will it mess anything else up?
-) if no problems arise, will it display a blank scrollbar like this textarea, -if- I have style declarations for it?

Thanks!
MrDoubtFire