Quick update: After a little more testing, I have realized that one of the fixes for IE5.5 actually doesn't do anything. Plus, it slows down the menus in all browsers. The other ie5.5 fix still seems to help.
So.... for fix #3 above I changed it as follows:

div#dropMenu li {
position:relative;
list-style:none;
margin:0;
float:left;
THIS STILL NEEDS TO BE CHANGED - /*line-height:1em;*/
width:16.667%;
*width:16.649%;
}

div#dropMenu ul.level1 {
width:70em;
margin:0 auto;
text-align:center;
background:#006699; /*background color of top menu when NOT selected. */
z-index:1000;
float:left;
}

KEEP THIS LINE AS IS!!!! - div#dropMenu li:hover {}
/*div#dropMenu li.submenu {background: url(../images/dropmenu.gif) 95% 50% no-repeat;} */
div#dropMenu li.submenu:hover {}