MultiSite Confusion…Questions

Apologies in advance for what may appear to be a series of “simple” questions but I’m having a hard time wrapping myself around a few things related to multisiting and need to go back to square 1.

Question #1: Network Content

Say I create 5 different networks each with their own “theme” where one network may be about sports; network 2 about cars; network 3 about women. Each network has it’s own BuddyPress install and blog subscribers. Say someone with a blog on the cars network creates a new post, someone with a blog creates a new post on women network, and another post from the sports network. I’d like for each of these posts to be displayed on the main site in their own widget or block. So I’d have a widget, or section, for latest 5 sports posts, latest 5 cars posts, and latest 5 women posts. Is it necessary to use RSS feeds for this or is there a way to do this using a plugin?

In addition I’d like for the latest “#” of users and groups from these networks to be displayed on the main site. To make things more “difficult” I’d like for the latest “#” blogs to also appear on the mainsite.

Can someone tell which of this is possible and which isn’t? I’m using the Mingle theme which makes it possible to create the customized layout I just need to know what method to apply in order to achieve the look.

Any assistance is appreciated.