What you may need to do is create a new button for new thread and edit the vbnewscms_sectionhead template.
Change this
Code:
<img border="0" src="$stylevar[imgdir_button]/newthread.gif" alt="$vbphrase[vbnews_newstory]" />
to the location of the new button.
Edit: another thing (based on your edit) you can change vbnewscms_articlebit to alter the width a little.
Change width="100%"
Code:
<table cellspacing="0" cellpadding="$stylevar[cellpadding]" border="0" class="tborder" width="100%">
to width="90%" and see if that doesn't help the width.