Hi,
Sorry for the delay.
It is possible to set the submenu to stay visible when you click on a submenu link - but only if the itemid of the menu is correct, some issues can be seen when using SEF components. You can see it here:
joomla15.simplebydesign.co.uk/joomla-overview
I am happy to check this for you if you can supply a link to your site or supply the debug code from the menu, you can enable this by add ?sdbDebug=1 or &sdbDebug=1 depending upon your URL structure.
As to the top menu item, you either need to so one of the following:
1) Use a separtor for the top menu item, not an actual link. Or
2) Use the following Parameters for the module:
Use Mouse Over: No
Top Menu As Link: No
Show Top Menu Link: Always
Expand Top Menu: Yes
Expand One Level Menu: Yes
Hope this should set the menu to work as you require, the Show Top Menu Link option is more optional, but if your top links are actual links you will be disabling them so its best to turn this option on.
Let me know how you get on.
Many Thanks