Site Sculptor can't be edited once created. You would probably have to start over by deleting the site that was created and clearing your database if you have accessed the live site.
To find the exact size you can usually view the .css that defines the measurements. I find Firebug very useful for finding the correct size of a particular area when viewed from a browser.
You can probably make the updates to the template after the pages have been generated from the wizard using dreamweaver. The page design will be inherited from a dreamweaver template that can be edited in dreamweaver directly.
The webassist FormBuilder product can create a form like you describe and send an email, and you could use DataAssist, or the built in Database Insert server behavior in Dreamweaver to insert the information into a databased.