Hello bryan-imhoff!
Thanks for your feedback.
There is no centralised database, all the voting, reward-distribution and staking mechanics are performed directly on the Steem blockchain using Steem-engine. Regarding cross-posting, there will be a specific tag for each post and if a user doesn't want to have the post show on Steemit, he can simply tick a box and it won't show on the Steemit interface.
Thanks for the reply, glad to hear the cross post will be optional! But again, just trying to get the model clear in my head. Rewards, voting, staking, all recorded on chain; but is the content? Obviously if I choose to cross post to Steem it will create a Steem post, but where is the content natively created in the Appics App by non Steem account holders being hosted? On Steem, EOS, a EOS-IO sidechain, or on a standard database? Being so photo centric as Appics is, this isn’t a huge deal I guess since photo hosting has always been off chain, but I’m just curious about the structure.