I think that this game is going to be 256 megabyte's and not like platinum 128. Since it probably will have Kanto. But if it has it, then it most definitely will be with smaller upgrades in the routes and buildings design.
In Europe there was no such thing. At least to my recollection. I got Colosseum without Pokemon Box and its the only game i gont have since Ruby/Sapphire.
Your math is actually pretty accurate ( but not right as you said yourself)
I guess i had about those battles in a hour or so to get my shiny Sableye and Mewtwo.