It took me some time to figure out what you meand by "clearer div". I converted the #menu block to float ... and it floated all over the place. It's working now, unless you resize the browser window too much.
I haven't installed Doulos SIL on my (rather recent) Linux installation. But several of the fonts here support the IPA extensions. The one in the logo is called Thryomenes (all good except bold-italic). Very beautiful results from Nimbus Mono, too.
At smaller sizes than the 75px logo, Century Schoolbook (sans or serif -- my standard fonts) and Free Mono give good results as well, and quite a number (Lucida, Free Sans and Serif, Helvetica, Times, URW Bookman ...) are acceptable. Note, these are alle GPL (or otherwise free) versions of the fonts, certainly available for Win, but I don't know how.
You were looking for #592, I think see this comprehensive unicode site. Their fonts list is obsolete, though, and Clearly U (which they recommend for Unix) is fine but the sizes are way too small. Without having installed any particular unicode font, I can see all but the last two symbols on this page.