need help with two problems of my header configuration

Hi I am new to Wordpress and Atahualpa. I am trying to set up a website here (http://www.varvoo.com/ji/), but it appears two problems:
1. The header image showed up on my actual webpage is always shorter than the original size which I put up there. Say, the original width of my header images were like 800 pix, but now they are all cut off and are much shorter. I set up my header area as 100% fluid. According to the explanation on the Alahualpa set up area, the max width of my header image should be the max of the screen. Can someone help me with this? I don't want the big white gap between my logo and my header images...

2. This problem doesn't show when I view the webpage using a laptop which is smaller than 15", but when I switch to a 21.5-inch iMac, the grey lines under the logo and the header images (as the background of the page menu) get inconsistent at both left side and the right side. I tried to adjust the settings for the header from fix to fluid, and I tried to change the Max and Minimum of the width. Both didn't work. Can someone help me with this as well?