In the map JS file, find the following code and remove it to prevent the default info window from opening:
// open info window for default address
if (isDefault) {
infowindow.open(map2,marker);
setTimeout("google.maps.event.trigger(wagmp_map_2_obj.markers[" + wagmp_map_2_obj.markers.length + "], 'click')",1000);
//map2.setCenter(point);
}
The Map CSS is set by the google API, to change styles, you would need to add the style to the map options, we do not offer support for this, but this page help:
http://gmaps-samples-v3.googlecode.com/svn/trunk/styledmaps/wizard/index.html?utm_medium=twitter