I am New to sharepoint platform Can anyone help regarding this

1) Search option in sharepoint 2007. I need to customize search control
according to our site branding.

2) Which css's should I modify while working with custom theme to get my site
branding. I have done modification using 1011-65001.css , but no luck with some
of the modifications for css.

3) While enabling FBA , I am not getting site actions and editing permissions
for authenticated users.