(Are you willing to shorten the SP power-down period to three to seven days from current period? )
Minimum is 7 days, anything below this would add too much instability.
(Are you willing to remove down-voting policy of STEEM blockchain? )
I wrote more than 3 years ago a proposal to mitigate this: https://steemit.com/steemit/@dragosroua/yavap-yet-another-voting-algorithm-proposal-or-what-i-actually-understand-by-proof-o-stake
(Are you willing to introduce smart contact into the STEEM block chain? )
Yes
(Are you willing to introduce a paid subscription model?)
Yes