Question about wp list pages and categories

Hello everybody.

I have actually two questions.
The first question is about the function “exclude Pages from List”
Lets say I want to exclude page 447 from the page listing.
<?php wp_list_pages(‘exclude=447&sort_order=DESC&title_li=’); ?>

What if I would like to have that page (and subpages) listed somewhere else in the sidebar?
Is there a way of doing that?

My second question is about categories.
I would like to exclude all posts in a certain category from the main page (where all entries appear)
However I would like the categoy to be listed in the category list.
Anyone know how I do this?

I hope I have explained it corectly..