1. Must I create a static website using xhtml, css and javascript first after which convert it to some wordpress theme. OR
  2. Must I directly begin to build the theme on your own. OR
  3. Must I use any framework OR
  4. Combination of the aforementioned.

I usually make use of the first method, but it might not be the greatest for you personally. After you have built a couple of you will probably possess a code base to merely place to your html/css.

You might obtain a pre-made theme having a layout like what your brand-new design has, and modify that. Its a terrific way to find out how styles are created

I'd recommend 3, beginning from the a current theme. It's simpler to remove (or ignore) than to need to implement on your own (or forget to implement which might hit you afterwards). The secret would be to begin with a style that's near to the thing you need without an excessive amount of bagage.

I'd also decided on a barebone theme according to HTML5 with shivs to aid older browsers. HTML5Boilerplate.com is most likely probably the most led HTML5 template project. It's a solid beginning point and several Wordpress styles derive from it. Google HTML5 boilerplate wordpress and perhaps barebone and you will find a number of templates. Here's one https://github.com/zencoder/html5-boilerplate-for-wordpress