Thanks, Chet!
Responding,
1) agreed, one table high cards for button to be used by all tables
2) agree with final table, but if there is a redraw at say 27 players I would think one table would then high card for button to be used at all 3 tables
3) I think to help provide more integrity to the game and to protect the floor person from being accused of favoritism, the seat cards should be randomly shuffled and then the high-card procedure would determine the first player to get the top of the seat card "deck" with the rest being distributed clockwise from that point! Without the high card, there may be some concern that the seat card "deck" is stacked in some way, with the first person getting some preferable position. Additionally, this method prevents the floor person from prematurely distributing the seat cards before the current hand is over (because the card deck would be required, and it is not available until the hand is over), allowing all players to move close to simultaneously, without leaving a heads up showdown behind.