Yup! You just go to their profile page (located at spoonbill.io/data/(username)) and hit the 'unsubscribe' button.
Yup! You just go to their profile page (located at spoonbill.io/data/(username)) and hit the 'subscribe' button.
Yup! You just go to spoonbill.io/data/(username).
Spoonbill launched in late 2016, so we've been tracking folks since around then -- however, we only have data for people who are followed by users, so it might not go back that far. In addition, we use Internet Archive to grab historical data as well, but that tends to be less fine-grained (an average account only has one or two Internet Archive snapshots every year.)
Yup. When you log in, tap your name: a dropdown will appear and RSS should be one of the options. (If you have any issues with getting RSS set up, definitely let me know.)
Email me and I'll get it taken care of immediately.