Realistically, only the last two apply to powers other than France and GB, since nothing can be done about the first. HOW important? Not that much.
But, the three issues above matter quite a bit to GB and France.
I've spent a lot of my EiA career playing France and I'd be prepared to forego the small (in my opinion) advantages of sequenced reinforcement.
Well, anybody playing GB under the current rules should agree with you in an instant (because they have a very unfavorable position compared to their old rules placement). I'll have to take your word for it about France, because I've never played her.
Still, someone asked the question (paraphrased) "what difference does it make?", and I've outlined the answers to that.
As I said earlier, diplomacy is far more important than reinforcement, and it is effectively simultaneous now (war declarations are not declared openly until the last person has finished, for instance). So, given the current rules, simultaneous diplo is fine. But, I would still prefer to have a much more structured diplo phase overall. However, that would make PBEM unplayable, so we compromise. :)
At LAST! The greatest campaign board game of all time is finally available for the PC. Can my old heart stand the strain?