I would also like to move the position of the 'pages' & add drop down menus.
You can move the pages and categories menus you have now to the bottom of the header area in the Imbalance 2 theme with the following CSS. Note that this CSS is just a start and is based on your current setup:
#header {
position: relative;
}
#header-left {
position: absolute;
width: 100%;
bottom: 30px;
}
#header-center {
position: absolute;
width: 100%;
bottom: 0;
}
.menu ul li {
float:left;
padding-right:20px;
}
Making dropdown menus work will take some work to change. If you can start by actually setting up some submenu items in your custom menus, I can take a look. The CSS to change it after that is not a simple change and it would help to have submenu items setup by you first.
This help page shows an example of how creating submenus works on the Appearance → Menus page: http://en.support.wordpress.com/menus/#changing-the-order-of-menu-items-and-creating-sub-menus