Hi frank2010,
You should be able to get rid of the scrollbar with a simple css tweak. By default, the twitter content area has the overflow property set to auto, which causes the scrollbar to be shown when the content exceeds the defined area. Setting overflow to hidden instead should get rid of the scrollbar for you, so you'd want to add a CSS override to your skin (via the CSS tab in Studio) that looks something like this:
#lia-body .lia-content .lia-component-twitter-widget-stream .lia-panel-content-wrapper .lia-twitter-stream-content-area {
overflow: hidden;
}
You can adjust the refresh interval of the stream in the admin by browsing to Features > Twitter Integration > Twitter Stream.
I hope this helps!