For extending things a bit, be sure to check out: http://docs.withknown.com/en/latest/plugins/community/ so you don't have to reinvent the wheel.
One of the things that made using my Known site much more addictive was being able to do so more easily on mobile. I wrote up a few thoughts here that you might appreciate: http://stream.boffosocko.com/2016/sharing-from-the-indieweb-on-mobile-android-with-apps-and
If you don't like the writing interface you might consider using Quill https://quill.p3k.io/ which uses micropub (already included in the core of Known). Micropub is now a W3C candidate as of yesterday. Alternate posting clients may be found at https://indieweb.org/micropub#Clients. In particular you might like OwnYourGram or OwnYourCheckin for Instagram and Foursquare if you use those.
You'll find lots of fellow devs and users of Known at https://indieweb.org/Known
Good luck and let us know if you need help!