my host server only supports .php as a SSI language.
I use dreamweaver and would like to know if i can only edit webpages in the code view for php and not in the the design view.

Well, you can do whatever you want, but I recommend learning to use Dreamweaver in code view exclusively. It does, however, recognize basic PHP includes inside of its display view, but it has difficulty parsing the display accurately, and won't display anything you do dynamically outside of including regular HTML files.