submenu's, rotating banners (og / conditional blocks),

Hey community,

i'm building my "first" drupal site and have a couple of questions.

env: drupal 6.13 / zen theme / og / signwriter / menuwriter block / a lot more...

Submenu:

I made a couple of menu's (one using the menu the signwriter - menuwriter block) and some have submenu items (no taxonomy used). Now i want something quite ordinary... Hide the subitems when the parent item isn't active. I thought that would be the normal behaviour but it isn't.

Conditional blocks (og) ???

I'not sure if my heading is right but can i use conditional blocks for those two issues:

1.) I want a different banner per organic group. How can i do that? And how can the og admin choose that image?
2.) And i want an own menu for each organic group. I installed og_menu but how to implement? (i don't wan't 50 menu's on a page)

regards Volkan