It’s a free platform for scheduling and managing Tweets, like Tweetdeck. Please note: anyone with a t.co shortened link will be able to navigate to the destination URL.
Twitter will use this to make your timeline better. There is no way to stop affiliates from adding their own custom payout on click using this parameter.
Your highest-level network tracker is always generated manually, but the other three levels can be generated automatically with campaign structure parameters. See if you are using Classic Analytics (ga.js) or Universal Analytics (analytics.js).