Since posts are made via UIs, the options available for choosing post payouts depends on UIs supporting the available options - for example steemit.com does not currently support splitting payouts between multiple beneficiaries, yet it can be done at the blockchain level and is done by other UIs. I thought that, as with beneficiaries, more options existed for SBD/Steem splits than is visible in the Seemit UI - but maybe not.
Rewards are part of the consensus, they do not depend on UI.
Since posts are made via UIs, the options available for choosing post payouts depends on UIs supporting the available options - for example steemit.com does not currently support splitting payouts between multiple beneficiaries, yet it can be done at the blockchain level and is done by other UIs. I thought that, as with beneficiaries, more options existed for SBD/Steem splits than is visible in the Seemit UI - but maybe not.
yep, not.
Also
not necessarily true. You can interact with the blockchain directly via the cli_wallet, if you wish...