I am currently having a huge headache trying to get a site I\'m building to work across variable resolutions. The main navigation is through an image map that needs to fill most
It's a little bit limited, but you CAN do irregular shapes with HTML/CSS.
A List Apart
CSS Play
You should be able to adapt one of those to your purposes.
EDIT:
Regarding image resizing, you need to use relative widths in your CSS instead of hardcoding them in pixels
In fact, there is a flexible framework that may already take care of much of that for you: Check out CSS Grid.