Would like to know how this "simultaneous planning, sequential execution" will be played in practice? 

A, everyone gives move/attack etc order to their fleet and then the turn resolves squentually? (If so wouldn't the fast fleets cause problems? the one who moves latter could hardly attack other fleets as they are moving away)

B, after everyone has finished the planning the players will move their fleet one by one.?

In any case I hope the game will be backed by a feature which allows a pbem or better yet pitboss-like gameplay (in civ 4's pitboss the game was constantly running on a server and players could log in at any time to make their turns then if everyone has finished or the timer run out the turn was executed. Moving units was kinda simultaneous, but during war players kept it sequential). 

In pbem everyone would get the same save, would made the turn, send it back then the host would run the turn and send the new save out.