It's more or less a Steem front end styled like crowdfunding, with the main benefits that it allows contribution via vote and helps you and your followers tally & track what their votes have added to the campaign value.
I believe that like most of the platforms, anything you post on Fundition will mirror here to Steemit because Steemit does not filter by origination point, but in order for things to show on Fundition and count as part of your campaign, you'll have to post there. The team did announce that they're working on an update to allow posting from other platforms to show and calculate on Fundition, so that founders can incorporate things like DLive streams into their campaigns.
The main key is that each new post made through Fundition creates a new voting target and extends the timeline of your campaign, so keep putting up some updates there and I'll keep voting them! I'd love to see this become one of the first success stories on Fundition.
Thanks for such a detailed eplanation. I was wondering about some of these things myself.