Can additional actions be added to steem power earning?

This is my self introduction. I work at a media company. We are investigating various ways of encouraging engagement on our UGC platform. Steem looks like a very exciting development and the mechanism for rewarding posting and voting seems both fair and likely to encourage essential behaviours on a social media network.

I wondering if over time additional actions can be added to the "earning' mechanism. Is one form of posting or media type more valuable than another? Is attracting new contributors to the network worth something? Can steem work with multiple social networks and UGC platforms. Can users on another platform authenticate with steem? All questions I'll be exploring over the next few weeks but also happy to chat about here.

Great to be part of the community.