How to expand given menu item?

Hi,

I got a question: how can I control the expansion of my menu?

I would like for example be able to initialize the menu by expanding by
default the tree to a certain level, for not having to click from the root
item to get the desired action.

Another application is updating the menu so that it follows the content of
the page, by that I mean when a page leads directly to another one without
passing by the appropriate menu item, to let the page expand itself the
menu.

Thanks for your help!

FoGia