To get the Fluid Grid Layout, you need to upgrade to Dreamweaver CC or CS6.
For Responsive Web Designs (RWD), you can do it manually with CSS Media Queries. David wrote a detailed tutorial below.
Introduction to CSS Media Queries
Or you can jump start your RWD projects with one of these popular Frameworks.
Initializr (HTML5 Boilerplate, Responsive or Bootstrap)
DMX Zone's Bootstrap FREE extension for DW