BuddyPress.org

Sorry if this is a really dumb question but I can’t really find the answer I have looked for.

I already have a wp-multisite installation live. It has several hundred members with blogs, a directory (directorypress) and a download store (estore).

I want to add a contributable gallery to my network, where members can add galleries and rate other members photos etc. I cannot find a way to do this using standard wordpress plugins, but I have been told there is functionality to do this may exist using buddypress.

My question is – can I just add buddypress and its plugins to my existing multisite? Will all the existing blogs still be as they are now etc? Or would adding buddypress now be incompatible?