It seems to take some time to get updated if I change in stylesheet.css.
This should be immediate with a refresh or a cache clear???
I also plan to put our logo at the top left corner of the header. How can I do this.
If this template has not altered the default coding - just make yours a gif and name it logo.gif and place it in this templates /images folder
If no support, should I modify the classic template that comes with the ZC install?
Looking at what you have - it might be simpler to copy all the classic template files and edit the template_info.php file with a template name of your choosing....
Read up on the overrides system in the tutorials